c语言函数part1.doc

部分c语言的函数以及用法 函数名: abort 功 能: 异常终止一个进程 用 法: void abort(void); 程序例: #include stdio.h #include stdlib.h int main(void) { printf(Calling abort()\n); abort(); return 0; /* This is never reached */ } 函数名: abs 功 能: 求整数的绝对值 用 法: int abs(int i); 程序例: #include stdio.h #include math.h int main(void) { int number = -1234; printf(number: %d absolute value: %d\n, number, abs(number)); return 0; } 函数名: absread, abswirte 功 能: 绝对磁盘扇区读、写数据 用 法: int absread(int drive, int nsects, int sectno, void *buffer); int abswrite(int drive, int nsects, in tsectno, void *buffer); 程序例: /* absread example */ #include stdio.h #include conio.h #include process.h #include dos.h int main(void) { int i, strt, ch_out, sector; char buf[512]; printf(Insert a diskette into drive A and press any key\n); getch(); sector = 0; if (absread(0, 1, sector, buf) != 0) { perror(Disk problem); exit(1); } printf(Read OK\n); strt = 3; for (i=0; i80; i++) { ch_out = buf[strt+i]; putchar(ch_out); } printf(\n); return(0); } 函数名: access 功 能: 确定文件的访问权限 用 法: int access(const char *filename, int amode); 程序例: #include stdio.h #include io.h int file_exists(char *filename); int main(void) { printf(Does NOTEXIST.FIL exist: %s\n, file_exists(NOTEXISTS.FIL) ? YES : NO); return 0; } int file_exists(char *filename) { return (access(filename, 0) == 0); } 函数名: acos 功 能: 反余弦函数 用 法: double acos(double x); 程序例: #include stdio.h #include math.h int main(void) { double result; double x = 0.5; result = acos(x); printf(The arc cosine of %lf is %lf\n, x, result); return 0; } 函数名: allocmem 功 能: 分配DOS存储段 用 法: int allocmem(unsigned size, unsigned *seg); 程序例: #include dos.h #include alloc.h #include stdio.h int main(void) { unsigned int size, segp; int stat; size = 64; /* (64 x 16) = 1024 bytes */ stat = allocmem(size, segp); if (stat == -1) printf(Allocated memory at segment: %x\n, segp); else printf(Failed: maximum number of paragra