*pathname, char *argv[], char *envp[]);
程序例:
/* execv example */
#include
#include
#include
void main(int argc, char *argv[])
{
int i;
printf("Command line arguments: ");
for (i=0; i
printf("[-] : %s ", i, argv[i]);
printf("About to exec child with arg1 arg2 ... ");
execv("CHILD.EXE", argv);
perror("exec error");
exit(1);
}
函数名:
exit
功 能: 终止程序
用 法: void exit(int status);
程序例:
#include
#include
#include
int main(void)
{
int status;
printf("Enter either 1 or 2 ");
status = getch();
/* Sets DOS errorlevel */
exit(status - ‘0‘);
/* Note: this line is never reached */
return 0;
}
函数名: gcvt
功 能: 把浮点数转换成字符串
用 法: char *gcvt(double value, int ndigit, char *buf);
程序例:
#include
#include
int main(void)
{
char str[25];
double num;
int sig = 5; /* significant digits */
/* a regular number */
num = 9.876;
gcvt(num, sig, str);
printf("string = %s ", str);
/* a negative number */
num = -123.4567;
gcvt(num, sig, str);
printf("string = %s ", str);
/* scientific notation */
num = 0.678e5;
gcvt(num, sig, str);
printf("string = %s ", str);
return(0);
}
函数名: geninterrupt
功 能: 产生一个软中断
用 法: void geninterrupt(int intr_num);
程序例:
#include
#include
/* function prototype */
void writechar(char ch);
int main(void)
{
clrscr();
gotoxy(80,25);
writechar(‘*‘);
getch();
return 0;
}
/*
outputs a character at the current cursor
position using the video BIOS to avoid the
scrolling of the screen when writing to
location (80,25).
*/
void writechar(char ch)
{
struct text_info ti;
/* grab current text settings */
gettextinfo(&ti);
/* interrupt 0x10 sub-function 9 */
_AH = 9;
/* character to be output */
_AL = ch;
_BH = 0; /* video page */
_BL = ti.attribute; /* video attribute */
_CX = 1; /* repetition factor */
geninterrupt(0x10); /* output the char */
}
函数名: getarccoords
功 能: 取得最后一次调用arc的坐标
用 法: void far getarccoords(struct arccoordstype far *arccoords);
程序例:
#include
#include
#include
#include
int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
struct arccoordstype arcinfo;
int midx, midy;
int stangle = 45, endangle = 270;
char sstr[80], estr[80];
/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");
/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s ",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}
midx = getmaxx() / 2;
midy = getmaxy() / 2;
/* draw arc and get coordinates */
setcolor(getmaxcolor());
arc(midx, mi