C语言实现求圆周长和面积函数

#include <stdio.h>

double area(double r, double *girth);

int main(void) {
    double r = 2.0;
    double girth = 0.0;
    double s = area(r, &girth);
    printf('圆的周长为：%.2lf，面积为：%.2lf\n', girth, s);
    return 0;
}

double area(double r, double *girth) {
    *girth = 2 * 3.14 * r;
    return 3.14 * r * r;
}