查找输入数字的立方，创建单独的显示函数

#include <stdio.h>  

void showCube(double x);  

int main(void){  
     double val;  
     printf("Enter a floating-point value: ");  
     scanf("%lf", &val);  
     showCube(val);  

    return 0;  
}

void showCube(double x) {  
    printf("The cube of %e is %e./n", x, x*x*x );  
}