C语言函数大全(c开头)

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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;

}