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    1. 站長資訊網(wǎng)
      最全最豐富的資訊網(wǎng)站

      C語言函數(shù)大全 f

      函數(shù)名: fabs
      功  能: 返回浮點數(shù)的絕對值
      用  法: double fabs(double x);
      程序例:

      #include <stdio.h>
      #include <math.h>

      int main(void)
      {
         float  number = -1234.0;

         printf(“number: %f  absolute value: %fn”,
         number, fabs(number));
         return 0;
      }
       
       
       

      函數(shù)名: farcalloc
      功  能: 從遠堆棧中申請空間
      用  法: void far *farcalloc(unsigned long units, unsigned ling unitsz);
      程序例:
      #include <stdio.h>
      #include <alloc.h>
      #include <string.h>
      #include <dos.h>

      int main(void)
      {
         char far *fptr;
         char *str = “Hello”;

         /* allocate memory for the far pointer */
         fptr = farcalloc(10, sizeof(char));

         /* copy “Hello” into allocated memory */
         /*
            Note: movedata is used because you
            might be in a small data model, in
            which case a normal string copy routine
            can not be used since it assumes the
            pointer size is near.
         */
         movedata(FP_SEG(str), FP_OFF(str),
           FP_SEG(fptr), FP_OFF(fptr),
                  strlen(str));

         /* display string (note the F modifier) */
         printf(“Far string is: %Fsn”, fptr);

         /* free the memory */
         farfree(fptr);

         return 0;
      }
       
       
       

      函數(shù)名: farcoreleft
      功  能: 返回遠堆中未作用存儲區(qū)大小
      用  法: long farcoreleft(void);
      程序例:

      #include <stdio.h>
      #include <alloc.h>

      int main(void)
      {
         printf(“The difference between the
          highest allocated block in the
                 farn”);
         printf(“heap and the top of the far heap
                 is: %lu bytesn”, farcoreleft());

         return 0;
      }
       
       
       

      函數(shù)名: farfree
      功  能: 從遠堆中釋放一塊
      用  法: void farfree(void);
      程序例:

      #include <stdio.h>
      #include <alloc.h>
      #include <string.h>
      #include <dos.h>

      int main(void)
      {
         char far *fptr;
         char *str = “Hello”;

         /* allocate memory for the far pointer */
         fptr = farcalloc(10, sizeof(char));

         /* copy “Hello” into allocated memory */
         /*
            Note: movedata is used because you might be in a small data model,
            in which case a normal string copy routine can’t be used since it
            assumes the pointer size is near.
         */
         movedata(FP_SEG(str), FP_OFF(str),
                  FP_SEG(fptr), FP_OFF(fptr),
                  strlen(str));

         /* display string (note the F modifier) */
         printf(“Far string is: %Fsn”, fptr);

         /* free the memory */
         farfree(fptr);

         return 0;
      }
       
       
       

      函數(shù)名: farmalloc
      功  能: 從遠堆中分配存儲塊
      用  法: void far *farmalloc(unsigned long size);
      程序例:

      #include <stdio.h>
      #include <alloc.h>
      #include <string.h>
      #include <dos.h>

      int main(void)
      {
         char far *fptr;
         char *str = “Hello”;

         /* allocate memory for the far pointer */
         fptr = farmalloc(10);

         /* copy “Hello” into allocated memory */
         /*
            Note: movedata is used because we might
            be in a small data model, in which case
            a normal string copy routine can not be
            used since it assumes the pointer size
            is near.
         */
         movedata(FP_SEG(str), FP_OFF(str),
           FP_SEG(fptr), FP_OFF(fptr),
           strlen(str));

         /* display string (note the F modifier) */
         printf(“Far string is: %Fsn”, fptr);

         /* free the memory */
         farfree(fptr);

         return 0;
      }
       
       
       

      函數(shù)名: farrealloc
      功  能: 調(diào)整遠堆中的分配塊
      用  法: void far *farrealloc(void far *block, unsigned long newsize);
      程序例:

      #include <stdio.h>
      #include <alloc.h>

      int main(void)
      {
         char far *fptr;

         fptr = farmalloc(10);
         printf(“First address: %Fpn”, fptr);
         fptr = farrealloc(fptr,20);
         printf(“New address  : %Fpn”, fptr);
         farfree(fptr);
         return 0;
      }
       
       

      函數(shù)名: fclose
      功  能: 關(guān)閉一個流
      用  法: int fclose(FILE *stream);
      程序例:

      #include <string.h>
      #include <stdio.h>

      int main(void)
      {
         FILE *fp;
         char buf[11] = “0123456789”;

         /* create a file containing 10 bytes */
         fp = fopen(“DUMMY.FIL”, “w”);
         fwrite(&buf, strlen(buf), 1, fp);

         /* close the file */
         fclose(fp);
         return 0;
      }
       
       
       

      函數(shù)名: fcloseall
      功  能: 關(guān)閉打開流
      用  法: int fcloseall(void);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         int streams_closed;

         /* open two streams */
         fopen(“DUMMY.ONE”, “w”);
         fopen(“DUMMY.TWO”, “w”);

         /* close the open streams */
         streams_closed = fcloseall();

         if (streams_closed == EOF)
            /* issue an error message */
            perror(“Error”);
         else
            /* print result of fcloseall() function */
            printf(“%d streams were closed.n”, streams_closed);

         return 0;
      }
       
       

      函數(shù)名: fcvt
      功  能: 把一個浮點數(shù)轉(zhuǎn)換為字符串
      用  法: char *fcvt(double value, int ndigit, int *decpt, int *sign);
      程序例:

      #include <stdlib.h>
      #include <stdio.h>
      #include <conio.h>

      int main(void)
      {
         char *string;
         double value;
         int dec, sign;
         int ndig = 10;

         clrscr();
         value = 9.876;
         string = ecvt(value, ndig, &dec, &sign);
         printf(“string = %s      dec = %d
                sign = %dn”, string, dec, sign);

         value = -123.45;
         ndig= 15;
         string = ecvt(value,ndig,&dec,&sign);
         printf(“string = %s dec = %d sign = %dn”,
                string, dec, sign);
       

         value = 0.6789e5; /* scientific
                              notation */
         ndig = 5;
         string = ecvt(value,ndig,&dec,&sign);
         printf(“string = %s           dec = %d
                sign = %dn”, string, dec, sign);

         return 0;
      }
       
       
       

      函數(shù)名: fdopen
      功  能: 把流與一個文件句柄相接
      用  法: FILE *fdopen(int handle, char *type);
      程序例:

      #include <sysstat.h>
      #include <stdio.h>
      #include <fcntl.h>
      #include <io.h>

      int main(void)
      {
         int handle;
         FILE *stream;

         /* open a file */
         handle = open(“DUMMY.FIL”, O_CREAT,
          S_IREAD | S_IWRITE);

         /* now turn the handle into a stream */
         stream = fdopen(handle, “w”);

         if (stream == NULL)
            printf(“fdopen failedn”);
         else
         {
            fprintf(stream, “Hello worldn”);
            fclose(stream);
         }
         return 0;
      }
       
       

      函數(shù)名: feof
      功  能: 檢測流上的文件結(jié)束符
      用  法: int feof(FILE *stream);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         FILE *stream;

         /* open a file for reading */
         stream = fopen(“DUMMY.FIL”, “r”);

         /* read a character from the file */
         fgetc(stream);

         /* check for EOF */
         if (feof(stream))
            printf(“We have reached end-of-filen”);

         /* close the file */
         fclose(stream);
         return 0;
      }
       
       

      函數(shù)名: ferror
      功  能: 檢測流上的錯誤
      用  法: int ferror(FILE *stream);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         FILE *stream;

         /* open a file for writing */
         stream = fopen(“DUMMY.FIL”, “w”);

         /* force an error condition by attempting to read */
         (void) getc(stream);

         if (ferror(stream))  /* test for an error on the stream */
         {
            /* display an error message */
            printf(“Error reading from DUMMY.FILn”);

            /* reset the error and EOF indicators */
            clearerr(stream);
         }

         fclose(stream);
         return 0;
      }
       
       
       

      函數(shù)名: fflush
      功  能: 清除一個流
      用  法: int fflush(FILE *stream);
      程序例:

      #include <string.h>
      #include <stdio.h>
      #include <conio.h>
      #include <io.h>

      void flush(FILE *stream);

      int main(void)
      {
         FILE *stream;
         char msg[] = “This is a test”;

         /* create a file */
         stream = fopen(“DUMMY.FIL”, “w”);

         /* write some data to the file */
         fwrite(msg, strlen(msg), 1, stream);

         clrscr();
         printf(“Press any key to flush
         DUMMY.FIL:”);
         getch();

         /* flush the data to DUMMY.FIL without
            closing it */
         flush(stream);

         printf(“nFile was flushed, Press any key
         to quit:”);
         getch();
         return 0;
      }

      void flush(FILE *stream)
      {
           int duphandle;

           /* flush the stream’s internal buffer */
           fflush(stream);

           /* make a duplicate file handle */
           duphandle = dup(fileno(stream));

           /* close the duplicate handle to flush
              the DOS buffer */
           close(duphandle);
      }
       
       
       

      函數(shù)名: fgetc
      功  能: 從流中讀取字符
      用  法: int fgetc(FILE *stream);
      程序例:

      #include <string.h>
      #include <stdio.h>
      #include <conio.h>

      int main(void)
      {
         FILE *stream;
         char string[] = “This is a test”;
         char ch;

         /* open a file for update */
         stream = fopen(“DUMMY.FIL”, “w+”);

         /* write a string into the file */
         fwrite(string, strlen(string), 1, stream);

         /* seek to the beginning of the file */
         fseek(stream, 0, SEEK_SET);

         do
         {
            /* read a char from the file */
            ch = fgetc(stream);

            /* display the character */
            putch(ch);
         } while (ch != EOF);

         fclose(stream);
         return 0;
      }
       
       
       

      函數(shù)名: fgetchar
      功  能: 從流中讀取字符
      用  法: int fgetchar(void);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         char ch;

         /* prompt the user for input */
         printf(“Enter a character followed by
         <Enter>: “);

         /* read the character from stdin */
         ch = fgetchar();

         /* display what was read */
         printf(“The character read is: ‘%c’n”,
                ch);
         return 0;
      }
       
       
       

      函數(shù)名: fgetpos
      功  能: 取得當前文件的句柄
      用  法: int fgetpos(FILE *stream);
      程序例:

      #include <string.h>
      #include <stdio.h>

      int main(void)
      {
         FILE *stream;
         char string[] = “This is a test”;
         fpos_t filepos;

         /* open a file for update */
         stream = fopen(“DUMMY.FIL”, “w+”);

         /* write a string into the file */
         fwrite(string, strlen(string), 1, stream);

         /* report the file pointer position */
         fgetpos(stream, &filepos);
         printf(“The file pointer is at byte
                %ldn”, filepos);

         fclose(stream);
         return 0;
      }
       
       
       

      函數(shù)名: fgets
      功  能: 從流中讀取一字符串
      用  法: char *fgets(char *string, int n, FILE *stream);
      程序例:

      #include <string.h>
      #include <stdio.h>

      int main(void)
      {
         FILE *stream;
         char string[] = “This is a test”;
         char msg[20];

         /* open a file for update */
         stream = fopen(“DUMMY.FIL”, “w+”);

         /* write a string into the file */
         fwrite(string, strlen(string), 1, stream);

         /* seek to the start of the file */
         fseek(stream, 0, SEEK_SET);

         /* read a string from the file */
         fgets(msg, strlen(string)+1, stream);

         /* display the string */
         printf(“%s”, msg);

         fclose(stream);
         return 0;
      }
       
       
       

      函數(shù)名: filelength
      功  能: 取文件長度字節(jié)數(shù)
      用  法: long filelength(int handle);
      程序例:

      #include <string.h>
      #include <stdio.h>
      #include <fcntl.h>
      #include <io.h>

      int main(void)
      {
         int handle;
         char buf[11] = “0123456789”;

         /* create a file containing 10 bytes */
         handle = open(“DUMMY.FIL”, O_CREAT);
         write(handle, buf, strlen(buf));

         /* display the size of the file */
         printf(“file length in bytes: %ldn”,
         filelength(handle));

         /* close the file */
         close(handle);
         return 0;
      }
       
       

      函數(shù)名: fillellipse
      功  能: 畫出并填充一橢圓
      用  法: void far fillellipse(int x, int y, int xradius, int yradius);
      程序例:

      #include <graphics.h>
      #include <conio.h>

      int main(void)
      {
         int gdriver = DETECT, gmode;
         int xcenter, ycenter, i;

         initgraph(&gdriver,&gmode,””);
         xcenter = getmaxx() / 2;
         ycenter = getmaxy() / 2;

         for (i=0; i<13; i++)
         {
            setfillstyle(i,WHITE);
            fillellipse(xcenter,ycenter,100,50);
            getch();
         }

         closegraph();
         return 0;
      }
       
       
       

      函數(shù)名: fillpoly
      功  能: 畫并填充一個多邊形
      用  法: void far fillpoly(int numpoints, int far *polypoints);
      程序例:

      #include <graphics.h>
      #include <stdlib.h>
      #include <stdio.h>
      #include <conio.h>

      int main(void)
      {
         /* request auto detection */
         int gdriver = DETECT, gmode, errorcode;
         int i, maxx, maxy;

         /* our polygon array */
         int poly[8];

         /* initialize graphics, local variables */
         initgraph(&gdriver, &gmode, “”);

         /* read result of initialization */
         errorcode = graphresult();
         if (errorcode != grOk)
         /* an error occurred */
         {
            printf(“Graphics error: %sn”,
                   grapherrormsg(errorcode));
            printf(“Press any key to halt:”);
            getch();
            exit(1);
            /* terminate with an error code */
         }

         maxx = getmaxx();
         maxy = getmaxy();

         poly[0] = 20;        /* 1st vertext */
         poly[1] = maxy / 2;

         poly[2] = maxx – 20; /* 2nd */
         poly[3] = 20;

         poly[4] = maxx – 50; /* 3rd */
         poly[5] = maxy – 20;

         /*
            4th vertex. fillpoly automatically
            closes the polygon.
         */
         poly[6] = maxx / 2;
         poly[7] = maxy / 2;

         /* loop through the fill patterns */
         for (i=EMPTY_FILL; i<USER_FILL; i++)
         {
            /* set fill pattern */
            setfillstyle(i, getmaxcolor());

            /* draw a filled polygon */
            fillpoly(4, poly);

            getch();
         }

         /* clean up */
         closegraph();
         return 0;
      }
       
       
       

      函數(shù)名: findfirst, findnext
      功  能: 搜索磁盤目錄; 取得下一個匹配的findfirst模式的文件
      用  法: int findfirst(char *pathname, struct ffblk *ffblk, int attrib);
       int findnext(struct ffblk *ffblk);
      程序例:

      /* findnext example */

      #include <stdio.h>
      #include <dir.h>

      int main(void)
      {
         struct ffblk ffblk;
         int done;
         printf(“Directory listing of *.*n”);
         done = findfirst(“*.*”,&ffblk,0);
         while (!done)
         {
            printf(”  %sn”, ffblk.ff_name);
            done = findnext(&ffblk);
         }

         return 0;
      }
       
       
       

      函數(shù)名: floodfill
      功  能: 填充一個有界區(qū)域
      用  法: void far floodfill(int x, int y, int border);
      程序例:

      #include <graphics.h>
      #include <stdlib.h>
      #include <stdio.h>
      #include <conio.h>

      int main(void)
      {
         /* request auto detection */
         int gdriver = DETECT, gmode, errorcode;
         int maxx, maxy;

         /* initialize graphics, local variables */
         initgraph(&gdriver, &gmode, “”);

         /* read result of initialization */
         errorcode = graphresult();
         if (errorcode != grOk)
         /* an error occurred */
         {
            printf(“Graphics error: %sn”,
                   grapherrormsg(errorcode));
            printf(“Press any key to halt:”);
            getch();
            exit(1);
            /* terminate with an error code */
         }

         maxx = getmaxx();
         maxy = getmaxy();

         /* select drawing color */
         setcolor(getmaxcolor());

         /* select fill color */
         setfillstyle(SOLID_FILL, getmaxcolor());

         /* draw a border around the screen */
         rectangle(0, 0, maxx, maxy);

         /* draw some circles */
         circle(maxx / 3, maxy /2, 50);
         circle(maxx / 2, 20, 100);
         circle(maxx-20, maxy-50, 75);
         circle(20, maxy-20, 25);

         /* wait for a key */
         getch();

         /* fill in bounded region */
         floodfill(2, 2, getmaxcolor());

         /* clean up */
         getch();
         closegraph();
         return 0;
      }
       
       
       

      函數(shù)名: floor
      功  能: 向下舍入
      用  法: double floor(double x);
      程序例:

      #include <stdio.h>
      #include <math.h>

      int main(void)
      {
         double number = 123.54;
         double down, up;

         down = floor(number);
         up = ceil(number);

         printf(“original number     %10.2lfn”,
                number);
         printf(“number rounded down %10.2lfn”,
                down);
         printf(“number rounded up   %10.2lfn”,
                up);

         return 0;
      }
       
       
       

      函數(shù)名: flushall
      功  能: 清除所有緩沖區(qū)
      用  法: int flushall(void);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         FILE *stream;

         /* create a file */
         stream = fopen(“DUMMY.FIL”, “w”);

         /* flush all open streams */
         printf(“%d streams were flushed.n”,
         flushall());

         /* close the file */
         fclose(stream);
         return 0;
      }
       
       
       

      函數(shù)名: fmod
      功  能: 計算x對y的模, 即x/y的余數(shù)
      用  法: double fmod(double x, double y);
      程序例:

      #include <stdio.h>
      #include <math.h>

      int main(void)
      {
         double x = 5.0, y = 2.0;
         double result;

         result = fmod(x,y);
         printf(“The remainder of (%lf / %lf) is
                %lfn”, x, y, result);
         return 0;
      }
       
       
       

      函數(shù)名: fnmerge
      功  能: 建立新文件名
      用  法: void fnerge(char *path, char *drive, char *dir);
      程序例:

      #include <string.h>
      #include <stdio.h>
      #include <dir.h>
       

      int main(void)
      {
          char s[MAXPATH];
          char drive[MAXDRIVE];
          char dir[MAXDIR];
          char file[MAXFILE];
          char ext[MAXEXT];

          getcwd(s,MAXPATH);              /* get the current working directory */
          strcat(s,”\”);                  /* append on a trailing character */
          fnsplit(s,drive,dir,file,ext); /* split the string to separate elems */
          strcpy(file,”DATA”);
          strcpy(ext,”.TXT”);
          fnmerge(s,drive,dir,file,ext);   /* merge everything into one string */
          puts(s);                                 /* display resulting string */

          return 0;
      }
       
       
       

      函數(shù)名: fopen
      功  能: 打開一個流
      用  法: FILE *fopen(char *filename, char *type);
      程序例:

      #include <stdlib.h>
      #include <stdio.h>
      #include <dir.h>

      int main(void)
      {
          char *s;
          char drive[MAXDRIVE];
          char dir[MAXDIR];
          char file[MAXFILE];
          char ext[MAXEXT];
          int flags;

          s=getenv(“COMSPEC”); /* get the comspec environment parameter */
          flags=fnsplit(s,drive,dir,file,ext);

          printf(“Command processor info:n”);
          if(flags & DRIVE)
             printf(“tdrive: %sn”,drive);
          if(flags & DIRECTORY)
             printf(“tdirectory: %sn”,dir);
          if(flags & FILENAME)
             printf(“tfile: %sn”,file);
          if(flags & EXTENSION)
             printf(“textension: %sn”,ext);

          return 0;
      }
       

      函數(shù)名: fprintf
      功  能: 傳送格式化輸出到一個流中
      用  法: int fprintf(FILE *stream, char *format[, argument,…]);
      程序例:

      /* Program to create backup of the
         AUTOEXEC.BAT file */

      #include <stdio.h>

      int main(void)
      {
         FILE *in, *out;

         if ((in = fopen(“\AUTOEXEC.BAT”, “rt”))
             == NULL)
         {
            fprintf(stderr, “Cannot open input
             file.n”);
            return 1;
         }

         if ((out = fopen(“\AUTOEXEC.BAK”, “wt”))
             == NULL)
         {
            fprintf(stderr, “Cannot open output
             file.n”);
            return 1;
         }

         while (!feof(in))
            fputc(fgetc(in), out);

         fclose(in);
         fclose(out);
         return 0;
      }
       
       
       

      函數(shù)名: FP_OFF
      功  能: 獲取遠地址偏移量
      用  法: unsigned FP_OFF(void far *farptr);
      程序例:

      /* FP_OFF */

      #include <dos.h>
      #include <stdio.h>

      int main(void)
      {
         char *str = “fpoff.c”;

         printf(“The offset of this file in memory
                is: %Fpn”, FP_OFF(str));

         return 0;
      }
       
       

      函數(shù)名: FP_SEG
      功  能: 獲取遠地址段值
      用  法: unsigned FP_SEG(void far *farptr);
      程序例:

      /* FP_SEG */

      #include <dos.h>
      #include <stdio.h>

      int main(void)
      {
         char *filename = “fpseg.c”;

         printf(“The offset of this file in memory
         is: %Fpn”, FP_SEG(filename));

         return(0);
      }
       
       
       

      函數(shù)名: fputc
      功  能: 送一個字符到一個流中
      用  法: int fputc(int ch, FILE *stream);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         char msg[] = “Hello world”;
         int i = 0;

         while (msg[i])
         {
            fputc(msg[i], stdout);
            i++;
         }
         return 0;
      }
       
       
       

      函數(shù)名: fputchar
      功  能: 送一個字符到標準輸出流(stdout)中
      用  法: int fputchar(char ch);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         char msg[] = “This is a test”;
         int i = 0;

         while (msg[i])
         {
            fputchar(msg[i]);
            i++;
         }
         return 0;
      }
       
       
       

      函數(shù)名: fputs
      功  能: 送一個字符到一個流中
      用  法: int fputs(char *string, FILE *stream);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         /* write a string to standard output */
         fputs(“Hello worldn”, stdout);

         return 0;
      }
       
       
       

      函數(shù)名: fread
      功  能: 從一個流中讀數(shù)據(jù)
      用  法: int fread(void *ptr, int size, int nitems, FILE *stream);
      程序例:

      #include <string.h>
      #include <stdio.h>

      int main(void)
      {
         FILE *stream;
         char msg[] = “this is a test”;
         char buf[20];

         if ((stream = fopen(“DUMMY.FIL”, “w+”))
             == NULL)
         {
            fprintf(stderr,
                    “Cannot open output file.n”);
            return 1;
         }

         /* write some data to the file */
         fwrite(msg, strlen(msg)+1, 1, stream);

         /* seek to the beginning of the file */
         fseek(stream, SEEK_SET, 0);

         /* read the data and display it */
         fread(buf, strlen(msg)+1, 1, stream);
         printf(“%sn”, buf);

         fclose(stream);
         return 0;
      }
       
       

      函數(shù)名: free
      功  能: 釋放已分配的塊
      用  法: void free(void *ptr);
      程序例:

      #include <string.h>
      #include <stdio.h>
      #include <alloc.h>

      int main(void)
      {
         char *str;

         /* allocate memory for string */
         str = malloc(10);

         /* copy “Hello” to string */
         strcpy(str, “Hello”);

         /* display string */
         printf(“String is %sn”, str);

         /* free memory */
         free(str);

         return 0;
      }
       

      函數(shù)名: freemem
      功  能: 釋放先前分配的DOS內(nèi)存塊
      用  法: int freemem(unsigned seg);
      程序例:

      #include <dos.h>
      #include <alloc.h>
      #include <stdio.h>

      int main(void)
      {
         unsigned int size, segp;
         int stat;

         size = 64; /* (64 x 16) = 1024 bytes */
         stat = allocmem(size, &segp);
         if (stat < 0)
            printf(“Allocated memory at segment:
            %xn”, segp);
         else
            printf(“Failed: maximum number of
            paragraphs available is %un”,
            stat);
         freemem(segp);

         return 0;
      }
       
       

      函數(shù)名: freopen
      功  能: 替換一個流
      用  法: FILE *freopen(char *filename, char *type, FILE *stream);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         /* redirect standard output to a file */
         if (freopen(“OUTPUT.FIL”, “w”, stdout)
             == NULL)
            fprintf(stderr, “error redirecting
                    stdoutn”);

         /* this output will go to a file */
         printf(“This will go into a file.”);

         /* close the standard output stream */
         fclose(stdout);

         return 0;
      }
       
       
       

      函數(shù)名: frexp
      功  能: 把一個雙精度數(shù)分解為尾數(shù)的指數(shù)
      用  法: double frexp(double value, int *eptr);
      程序例:

      #include <math.h>
      #include <stdio.h>

      int main(void)
      {
         double mantissa, number;
         int exponent;

         number = 8.0;
         mantissa = frexp(number, &exponent);

         printf(“The number %lf is “, number);
         printf(“%lf times two to the “, mantissa);
         printf(“power of %dn”, exponent);

         return 0;
      }
       
       

      函數(shù)名: fscanf
      功  能: 從一個流中執(zhí)行格式化輸入
      用  法: int fscanf(FILE *stream, char *format[,argument…]);
      程序例:

      #include <stdlib.h>
      #include <stdio.h>

      int main(void)
      {
         int i;

         printf(“Input an integer: “);

         /* read an integer from the
            standard input stream */
         if (fscanf(stdin, “%d”, &i))
            printf(“The integer read was: %in”,
                   i);
         else
         {
            fprintf(stderr, “Error reading an
                    integer from stdin.n”);
            exit(1);
         }
         return 0;
      }
       
       
       

      函數(shù)名: fseek
      功  能: 重定位流上的文件指針
      用  法: int fseek(FILE *stream, long offset, int fromwhere);
      程序例:

      #include <stdio.h>

      long filesize(FILE *stream);

      int main(void)
      {
         FILE *stream;

         stream = fopen(“MYFILE.TXT”, “w+”);
         fprintf(stream, “This is a test”);
         printf(“Filesize of MYFILE.TXT is %ld bytesn”, filesize(stream));
         fclose(stream);
         return 0;
      }

      long filesize(FILE *stream)
      {
         long curpos, length;

         curpos = ftell(stream);
         fseek(stream, 0L, SEEK_END);
         length = ftell(stream);
         fseek(stream, curpos, SEEK_SET);
         return length;
      }
       
       
       
       
       

      函數(shù)名: fsetpos
      功  能: 定位流上的文件指針
      用  法: int fsetpos(FILE *stream, const fpos_t *pos);
      程序例:

      #include <stdlib.h>
      #include <stdio.h>

      void showpos(FILE *stream);

      int main(void)
      {
         FILE *stream;
         fpos_t filepos;

         /* open a file for update */
         stream = fopen(“DUMMY.FIL”, “w+”);

         /* save the file pointer position */
         fgetpos(stream, &filepos);

         /* write some data to the file */
         fprintf(stream, “This is a test”);

         /* show the current file position */
         showpos(stream);

         /* set a new file position, display it */
         if (fsetpos(stream, &filepos) == 0)
           showpos(stream);
         else
         {
            fprintf(stderr, “Error setting file
             pointer.n”);
            exit(1);
         }

         /* close the file */
         fclose(stream);
         return 0;
      }

      void showpos(FILE *stream)
      {
         fpos_t pos;

         /* display the current file pointer
            position of a stream */
         fgetpos(stream, &pos);
         printf(“File position: %ldn”, pos);
      }
       

      函數(shù)名: fstat
      功  能: 獲取打開文件信息
      用  法: int fstat(char *handle, struct stat *buff);
      程序例:

      #include <sysstat.h>
      #include <stdio.h>
      #include <time.h>

      int main(void)
      {
         struct stat statbuf;
         FILE *stream;

         /* open a file for update */
         if ((stream = fopen(“DUMMY.FIL”, “w+”))
             == NULL)
         {
            fprintf(stderr, “Cannot open output
                    file.n”);
            return(1);
         }
         fprintf(stream, “This is a test”);
         fflush(stream);

         /* get information about the file */
         fstat(fileno(stream), &statbuf);
         fclose(stream);

         /* display the information returned */
         if (statbuf.st_mode & S_IFCHR)
            printf(“Handle refers to a device.n”);
         if (statbuf.st_mode & S_IFREG)
            printf(“Handle refers to an ordinary
                   file.n”);
         if (statbuf.st_mode & S_IREAD)
            printf(“User has read permission on
                   file.n”);
         if (statbuf.st_mode & S_IWRITE)
            printf(“User has write permission on
                    file.n”);

         printf(“Drive letter of file: %cn”,
         ‘A’+statbuf.st_dev);
         printf(“Size of file in bytes: %ldn”,
         statbuf.st_size);
         printf(“Time file last opened: %sn”,
         ctime(&statbuf.st_ctime));
         return 0;
      }
       
       
       

      函數(shù)名: ftell
      功  能: 返回當前文件指針
      用  法: long ftell(FILE *stream);
      程序例:

      #include <stdio.h>

      int main(void)
      {
         FILE *stream;

         stream = fopen(“MYFILE.TXT”, “w+”);
         fprintf(stream, “This is a test”);
         printf(“The file pointer is at byte
                %ldn”, ftell(stream));
         fclose(stream);
         return 0;
      }
       
       
       

      函數(shù)名: fwrite
      功  能: 寫內(nèi)容到流中
      用  法: int fwrite(void *ptr, int size, int nitems, FILE *stream);
      程序例:

      #include <stdio.h>

      struct mystruct
      {
        int i;
        char ch;
      };

      int main(void)
      {
         FILE *stream;
         struct mystruct s;

         if ((stream = fopen(“TEST.$$$”, “wb”)) == NULL) /* open file TEST.$$$ */
         {
            fprintf(stderr, “Cannot open output file.n”);
            return 1;
         }
         s.i = 0;
         s.ch = ‘A’;
         fwrite(&s, sizeof(s), 1, stream); /* write struct s to file */
         fclose(stream); /* close file */
         return 0;
      }

       

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