C语言的函数!

内财数模协会 · 发表于 2004-5-8 17:35:43

<

>函数名: fgetpos
功能: 取得当前文件的句柄
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\
%ld\n", filepos); fclose(stream);
return 0;
}

内财数模协会 · 发表于 2004-5-8 17:35:54

<

>函数名: fgets
功能: 从流中读取一字符串
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;
}

内财数模协会 · 发表于 2004-5-8 17:36:05

<

>函数名: filelength
功能: 取文件长度字节数
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: %ld\n",
filelength(handle)); /* close the file */
close(handle);
return 0;
}

内财数模协会 · 发表于 2004-5-8 17:36:13

<

>函数名: fillellipse
功能: 画出并填充一椭圆
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;
}

内财数模协会 · 发表于 2004-5-8 17:36:25

<

>函数名: fillpoly
功能: 画并填充一个多边形
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: %s\n",
 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;
}

内财数模协会 · 发表于 2004-5-8 17:36:34

<

>函数名: findfirst, findnext
功能: 搜索磁盘目录; 取得下一个匹配的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(" %s\n", ffblk.ff_name);
done = findnext(&ffblk);
} return 0;
}

内财数模协会 · 发表于 2004-5-8 17:36:43

<

>函数名: floodfill
功能: 填充一个有界区域
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: %s\n",
 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;
}

内财数模协会 · 发表于 2004-5-8 17:36:52

<

>函数名: 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 %10.2lf\n",
 number);
printf("number rounded down %10.2lf\n",
 down);
printf("number rounded up %10.2lf\n",
 up); return 0;
}

内财数模协会 · 发表于 2004-5-8 17:37:00

<

>函数名: flushall
功能: 清除所有缓冲区
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;
}

内财数模协会 · 发表于 2004-5-8 17:37:09

<

>函数名: fmod
功能: 计算x对y的模, 即x/y的余数
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 \
 %lf\n", x, y, result);
return 0;
}

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