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 #include #include
int sort_function( const void *a, const void *b); char list[5][4] = { \"cat\int main(void) { int x;
qsort((void *)list, 5, sizeof(list[0]), sort_function); for (x = 0; x < 5; x++) printf(\"%s\\n\return 0; }
int sort_function( const void *a, const void *b) {
return( strcmp(a,b) ); }
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 #include #include
int sort_function( const void *a, const void *b); char list[5][4] = { \"cat\int main(void) { int x;
qsort((void *)list, 5, sizeof(list[0]), sort_function); for (x = 0; x < 5; x++) printf(\"%s\\n\return 0; }
int sort_function( const void *a, const void *b) {
return( strcmp(a,b) ); }
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
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; }
函数名: rand
功 能: 随机数发⽣器 ⽤ 法: void rand(void); 程序例: #include #include
int main(void) { int i;
printf(\"Ten random numbers from 0 to 99\\n\\n\"); for(i=0; i<10; i++)
printf(\"%d\\n\return 0; }
函数名: randbrd 功 能: 随机块读
⽤ 法: int randbrd(struct fcb *fcbptr, int reccnt); 程序例: #include #include #include #include
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\/* 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[i]);
/* restore previous dta */ setdta(save_dta); return 0; }
函数名: randbwr 功 能: 随机块写
⽤ 法: int randbwr(struct fcp *fcbptr, int reccnt); 程序例: #include #include #include #include
int main(void) {
char far *save_dta; char line[80];
char buffer[256] = \"RANDBWR test!\"; struct fcb blk; int result;
/* get new file name from user */
printf(\"Enter a file name to create (no path - ie. a:file.dat\\n\"); gets(line);
/* parse the new file name to the dta */ parsfnm(line,&blk,1);
printf(\"Drive #%d File: %s\\n\/* request DOS services to create file */ if (bdosptr(0x16, &blk, 0) == -1) {
perror(\"Error creating file\"); exit(1); }
/* save old dta and set new dta */ save_dta = getdta(); setdta(buffer);
/* write new records */ blk.fcb_recsize = 256; blk.fcb_random = 0L; result = randbwr(&blk, 1); if (!result)
printf(\"Write OK\\n\"); else {
perror(\"Disk error\"); exit(1); }
/* request DOS services to close the file */ if (bdosptr(0x10, &blk, 0) == -1) {
perror(\"Error closing file\"); exit(1); }
/* reset the old dta */ setdta(save_dta); return 0; }
函数名: random 功 能: 随机数发⽣器
⽤ 法: int random(int num); 程序例:
#include #include #include
/* prints a random number in the range 0 to 99 */ int main(void) {
randomize();
printf(\"Random number in the 0-99 range: %d\\n\return 0; }
函数名: randomize
功 能: 初始化随机数发⽣器 ⽤ 法: void randomize(void); 程序例: #include #include #include
int main(void) { int i;
randomize();
printf(\"Ten random numbers from 0 to 99\\n\\n\"); for(i=0; i<10; i++)
printf(\"%d\\n\return 0; }
函数名: read
功 能: 从⽂件中读
⽤ 法: int read(int handle, void *buf, int nbyte); 程序例: #include #include #include #include #include #include
int main(void) {
void *buf;
int handle, bytes; buf = malloc(10); /*
Looks for a file in the current directory named TEST.$$$ and attempts to read 10 bytes from it. To use this example you should create the file TEST.$$$ */
if ((handle =
open(\"TEST.$$$\{
printf(\"Error Opening File\\n\"); exit(1); }
if ((bytes = read(handle, buf, 10)) == -1) { printf(\"Read Failed.\\n\"); exit(1); }
else {
printf(\"Read: %d bytes read.\\n\
}
return 0; }
函数名: realloc
功 能: 重新分配主存
⽤ 法: void *realloc(void *ptr, unsigned newsize); 程序例: #include #include #include
int main(void) {
char *str;
/* allocate memory for string */ str = malloc(10);
/* copy \"Hello\" into string */ strcpy(str, \"Hello\");
printf(\"String is %s\\n Address is %p\\n\str = realloc(str, 20);
printf(\"String is %s\\n New address is %p\\n\/* free memory */ free(str); return 0; }
函数名: rectangle 功 能: 画⼀个矩形
⽤ 法: void far rectangle(int left, int top, int right, int bottom); 程序例: #include #include #include #include
int main(void) {
/* request auto detection */
int gdriver = DETECT, gmode, errorcode; int left, top, right, bottom;
/* 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\printf(\"Press any key to halt:\"); getch();
exit(1); /* terminate with an error code */ }
left = getmaxx() / 2 - 50; top = getmaxy() / 2 - 50; right = getmaxx() / 2 + 50; bottom = getmaxy() / 2 + 50; /* draw a rectangle */
rectangle(left,top,right,bottom); /* clean up */ getch();
closegraph(); return 0;
}
函数名: registerbgidriver
功 能: 登录已连接进来的图形驱动程序代码 ⽤ 法: int registerbgidriver(void(*driver)(void)); 程序例: #include #include #include #include
int main(void) {
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
/* register a driver that was added into graphics.lib */ errorcode = registerbgidriver(EGAVGA_driver); /* report any registration errors */ if (errorcode < 0) {
printf(\"Graphics error: %s\\n\printf(\"Press any key to halt:\"); getch();
exit(1); /* terminate with an error code */ }
/* 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\printf(\"Press any key to halt:\"); getch();
exit(1); /* terminate with an error code */ }
/* draw a line */
line(0, 0, getmaxx(), getmaxy()); /* clean up */ getch();
closegraph(); return 0; }
函数名: remove 功 能: 删除⼀个⽂件
⽤ 法: int remove(char *filename); 程序例: #include
int main(void) {
char file[80];
/* prompt for file name to delete */ printf(\"File to delete: \"); gets(file);
/* delete the file */ if (remove(file) == 0)
printf(\"Removed %s.\\n\else
perror(\"remove\"); return 0;
}
函数名: rename 功 能: 重命名⽂件
⽤ 法: int rename(char *oldname, char *newname); 程序例: #include
int main(void) {
char oldname[80], newname[80];
/* prompt for file to rename and new name */ printf(\"File to rename: \"); gets(oldname);
printf(\"New name: \"); gets(newname); /* Rename the file */
if (rename(oldname, newname) == 0)
printf(\"Renamed %s to %s.\\n\else
perror(\"rename\"); return 0; }
函数名: restorecrtmode
功 能: 将屏幕模式恢复为先前的imitgraph设置 ⽤ 法: void far restorecrtmode(void); 程序例: #include #include #include #include
int main(void) {
/* request auto detection */
int gdriver = DETECT, gmode, errorcode; int x, y;
/* 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\printf(\"Press any key to halt:\"); getch();
exit(1); /* terminate with an error code */ }
x = getmaxx() / 2; y = getmaxy() / 2;
/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT); outtextxy(x, y, \"Press any key to exit graphics:\"); getch();
/* restore system to text mode */ restorecrtmode();
printf(\"We’re now in text mode.\\n\");
printf(\"Press any key to return to graphics mode:\"); getch();
/* return to graphics mode */
setgraphmode(getgraphmode());
/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT); outtextxy(x, y, \"We’re back in graphics mode.\");
outtextxy(x, y+textheight(\"W\"), \"Press any key to halt:\"); /* clean up */ getch();
closegraph(); return 0; }
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