Calculate harmonic mean of two numbers using macro - C Preprocessor

C examples for Preprocessor:Macro

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Introduction

The harmonic mean of two numbers is obtained by taking the inverses of the two numbers, averaging them, and taking the inverse of the result.

Demo Code

        
#include <stdio.h>  
#define HMEAN(X,Y) (2.0 * (X) *(Y) / ((X) + (Y)))  

int main(void)  {  
    double x, y, ans;  
      //w  w  w.j  a  v a2 s .co m
    puts("Enter a pair of numbers (q to quit): ");  
    while (scanf("%lf %lf", &x, &y) == 2)  
    {  
        ans = HMEAN(x,y);  
        printf("%g = harmonic mean of %g %g.\n", ans, x, y);  
        
        printf(" see if works with arithmetic expressions \n ");
        ans = HMEAN(x + y, x * y);  
        printf("%g = harmonic mean of %g %g.\n", ans, x + y, x * y);  
        puts("Enter a pair of numbers (q to quit): ");  
    }  
    puts("Bye");  
      
    return 0;  
}

Result


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