C语言的函数!

内财数模协会 · 发表于 2004-5-10 16:27:12

<

>函数名: putenv
功能: 把字符串加到当前环境中
用法: int putenv(char *envvar);
程序例: <

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

>int main(void)
{
char *path, *ptr;
int i = 0; /* get the current path environment */
ptr = getenv("PATH"); /* set up new path */
path = malloc(strlen(ptr)+15);
strcpy(path,"PATH=");
strcat(path,ptr);
strcat(path,";c:\\temp"); /* replace the current path and display current environment */
putenv(path);
while (environ)
 printf("%s\n",environ[i++]); return 0;
}

内财数模协会 · 发表于 2004-5-10 16:27:29

<

>函数名: putimage
功能: 在屏幕上输出一个位图
用法: void far putimage(int x, int y, void far *bitmap, int op);
程序例: <

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

>#define ARROW_SIZE 10 void draw_arrow(int x, int y); int main(void)
{
/* request autodetection */
int gdriver = DETECT, gmode, errorcode;
void *arrow;
int x, y, maxx;
unsigned int size; /* initialize graphics and 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();
x = 0;
y = getmaxy() / 2; /* draw the image to be grabbed */
draw_arrow(x, y); /* calculate the size of the image */
size = imagesize(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE); /* allocate memory to hold the image */
arrow = malloc(size); /* grab the image */
getimage(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE, arrow); /* repeat until a key is pressed */
while (!kbhit())
{
 /* erase old image */
 putimage(x, y-ARROW_SIZE, arrow, XOR_PUT); x += ARROW_SIZE;
 if (x >= maxx)
 x = 0; /* plot new image */
 putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
} /* clean up */
free(arrow);
closegraph();
return 0;
} void draw_arrow(int x, int y)
{
/* draw an arrow on the screen */
moveto(x, y);
linerel(4*ARROW_SIZE, 0);
linerel(-2*ARROW_SIZE, -1*ARROW_SIZE);
linerel(0, 2*ARROW_SIZE);
linerel(2*ARROW_SIZE, -1*ARROW_SIZE);
}

内财数模协会 · 发表于 2004-5-10 16:27:55

<

>函数名: putpixel
功能: 在指定位置画一像素
用法: void far putpixel (int x, int y, int pixelcolor);
程序例: <

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

>#define PIXEL_COUNT 1000
#define DELAY_TIME 100 /* in milliseconds */ int main(void)
{
/* request autodetection */
int gdriver = DETECT, gmode, errorcode;
int i, x, y, color, maxx, maxy, maxcolor, seed; /* initialize graphics and 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() + 1;
maxy = getmaxy() + 1;
maxcolor = getmaxcolor() + 1; while (!kbhit())
{
 /* seed the random number generator */
 seed = random(32767);
 srand(seed);
 for (i=0; i<PIXEL_COUNT; i++)
 {
 x = random(maxx);
 y = random(maxy);
 color = random(maxcolor);
 putpixel(x, y, color);
 } delay(DELAY_TIME);
 srand(seed);
 for (i=0; i<PIXEL_COUNT; i++)
 {
 x = random(maxx);
 y = random(maxy);
 color = random(maxcolor);
 if (color == getpixel(x, y))
 putpixel(x, y, 0);
 }
} /* clean up */
getch();
closegraph();
return 0;
}

内财数模协会 · 发表于 2004-5-10 16:28:14

<

>函数名: puts
功能: 送一字符串到流中
用法: int puts(char *string);
程序例: <

>#include <stdio.h>
int main(void)
{
char string[] = "This is an example output string\n"; <

> puts(string);
return 0;
}

内财数模协会 · 发表于 2004-5-10 16:28:27

<

>函数名: puttext
功能: 将文本从存储区拷贝到屏幕
用法: int puttext(int left, int top, int right, int bottom, void *source);
程序例: <

>#include <conio.h>
int main(void)
{
char buffer[512]; <

> /* put some text to the console */
clrscr();
gotoxy(20, 12);
cprintf("This is a test. Press any key to continue ...");
getch(); /* grab screen contents */
gettext(20, 12, 36, 21,buffer);
clrscr(); /* put selected characters back to the screen */
gotoxy(20, 12);
puttext(20, 12, 36, 21, buffer);
getch(); return 0;
}

内财数模协会 · 发表于 2004-5-10 16:28:39

<

>函数名: putw
功能: 把一字符或字送到流中
用法: int putw(int w, FILE *stream);
程序例: <

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

>#define FNAME "test.$$$" int main(void)
{
FILE *fp;
int word; /* place the word in a file */
fp = fopen(FNAME, "wb");
if (fp == NULL)
{
 printf("Error opening file %s\n", FNAME);
 exit(1);
} word = 94;
putw(word,fp);
if (ferror(fp))
 printf("Error writing to file\n");
else
 printf("Successful write\n");
fclose(fp); /* reopen the file */
fp = fopen(FNAME, "rb");
if (fp == NULL)
{
 printf("Error opening file %s\n", FNAME);
 exit(1);
} /* extract the word */
word = getw(fp);
if (ferror(fp))
 printf("Error reading file\n");
else
 printf("Successful read: word = %d\n", word); /* clean up */
fclose(fp);
unlink(FNAME); return 0;
}

内财数模协会 · 发表于 2004-5-10 16:29:19

<

>函数名: qsort
功能: 使用快速排序例程进行排序
用法: void qsort(void *base, int nelem, int width, int (*fcmp)());
程序例: <

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

>int sort_function( const void *a, const void *b); char list[5][4] = { "cat", "car", "cab", "cap", "can" };
 int main(void)
{
int x; qsort((void *)list, 5, sizeof(list[0]), sort_function);
for (x = 0; x < 5; x++)
 printf("%s\n", list[x]);
return 0;
} int sort_function( const void *a, const void *b)
{
return( strcmp(a,b) );
}

内财数模协会 · 发表于 2004-5-10 16:29:58

<

>函数名: raise
功能: 向正在执行的程序发送一个信号
用法: int raise(int sig);
程序例: <

>#include <signal.h> <

>int main(void)
{
int a, b; a = 10;
b = 0;
if (b == 0)
/* preempt divide by zero error */
raise(SIGFPE);
a = a / b;
return 0;
}

内财数模协会 · 发表于 2004-5-10 16:30:08

<

>函数名: rand
功能: 随机数发生器
用法: void rand(void);
程序例: <

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

>int main(void)
{
int i; printf("Ten random numbers from 0 to 99\n\n");
for(i=0; i<10; i++)
printf("%d\n", rand() % 100);
return 0;
}

内财数模协会 · 发表于 2004-5-10 16:30:21

<

>函数名: randbrd
功能: 随机块读
用法: int randbrd(struct fcb *fcbptr, int reccnt);
程序例: <

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

>int main(void)
{
char far *save_dta;
char line[80], buffer[256];
struct fcb blk;
int i, result; /* get user input file name for dta */
printf("Enter drive and file name (no path - i.e. a:file.dat)\n");
gets(line); /* put file name in fcb */
if (!parsfnm(line, &blk, 1))
{
 printf("Error in call to parsfnm\n");
 exit(1);
}
printf("Drive #%d File: %s\n\n", blk.fcb_drive, blk.fcb_name); /* open file with DOS FCB open file */
bdosptr(0x0F, &blk, 0); /* save old dta, and set new one */
save_dta = getdta();
setdta(buffer); /* set up info for the new dta */
blk.fcb_recsize = 128;
blk.fcb_random = 0L;
result = randbrd(&blk, 1); /* check results from randbrd */
if (!result)
 printf("Read OK\n\n");
else
{
 perror("Error during read");
 exit(1);
} /* read in data from the new dta */
printf("The first 128 characters are:\n");
for (i=0; i<128; i++)
 putchar(buffer); /* restore previous dta */
setdta(save_dta); return 0;
}

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