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1、E：函数名: ecvt功 能: 把一个浮点数转换为字符串用 法: char ecvt(double value, int ndigit, int *decpt, int *sign);程序例: #include #include #include 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 = %d
2、n, 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);
3、return 0;函数名: ellipse功 能: 画一椭圆用 法: void far ellipse(int x, int y, int stangle, int endangle, int xradius, int yradius);程序例:#include #include #include #include int main(void) /* request auto detection */ int gdriver = DETECT, gmode, errorcode; int midx, midy; int stangle = 0, endangle = 360; int xrad
4、ius = 100, yradius = 50; /* 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
5、(); exit(1); /* terminate with an error code */ midx = getmaxx() / 2; midy = getmaxy() / 2; setcolor(getmaxcolor(); /* draw ellipse */ ellipse(midx, midy, stangle, endangle, xradius, yradius); /* clean up */ getch(); closegraph(); return 0;函数名: enable功 能: 开放硬件中断用 法: void enable(void);程序例:/* * NOTE:T
6、his is an interrupt service routine. You can NOT compile this programwith Test Stack Overflow turned on and get an executable file which willoperate correctly.*/#include #include #include /* The clock tick interrupt */#define INTR 0X1Cvoid interrupt ( *oldhandler)(void);int count=0;void interrupt ha
7、ndler(void)/* disable interrupts during the handling of the interrupt*/ disable();/* increase the global counter */ count+;/* re enable interrupts at the end of the handler*/ enable();/* call the old routine */ oldhandler();int main(void)/* save the old interrupt vector */ oldhandler = getvect(INTR)
8、;/* install the new interrupt handler */ setvect(INTR, handler);/* loop until the counter exceeds 20 */ while (count 20) printf(count is %dn,count);/* reset the old interrupt handler */ setvect(INTR, oldhandler); return 0;函数名: exec.功 能: 装入并运行其它程序的函数用 法: int execl(char *pathname, char *arg0, arg1, .,
9、 argn, NULL);int execle(char *pathname, char *arg0, arg1, ., argn, NULL, char *envp);int execlp(char *pathname, char *arg0, arg1, ., NULL);int execple(char *pathname, char *arg0, arg1, ., NULL, char *envp);int execv(char *pathname, char *argv);int execve(char *pathname, char *argv, char *envp);int e
10、xecvp(char *pathname, char *argv);int execvpe(char *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:n); for (i=0; iargc; i+) printf(%2d : %sn, i, argvi); printf(About to exec child with arg1 arg2 .n); execv(CHILD.EXE, argv); perror(exec error); exit(1);
