C语言函数大全(c开头)

函数名: cabs

功能: 计算复数的绝对值

用法: double cabs(struct complex z);

程序例:

#include
#include
int main(void)
{
struct complex z;
double val;
z.x = 2.0;
z.y = 1.0;
val = cabs(z);
printf("The absolute value of %.2lfi %.2lfj is %.2lf", z.x, z.y, val);
return 0;
}

函数名: calloc

功能: 分配主存储器

用法: void *calloc(size_t nelem, size_t elsize);

程序例:

#include
#include
int main(void)
{
char *str = NULL;
/* allocate memory for string */
str = calloc(10, sizeof(char));
/* copy "Hello" into string */
strcpy(str, "Hello");
/* display string */
printf("String is %s\n", str);
/* free memory */
free(str);
return 0;
}

函数名: ceil

功能: 向上舍入

用法: double ceil(double x);

程序例:

#include
#include
int main(void)
{
double number = 123.54;
double down, up;
down = floor(number);
up = ceil(number);
printf("original number %5.2lf\n", number);
printf("number rounded down %5.2lf\n", down);
printf("number rounded up %5.2lf\n", up);
return 0;
}