Implements a menu using an array of pointers to functions - C Array

C examples for Array:Array Value

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Description

Implements a menu using an array of pointers to functions

Demo Code

#include <stdio.h>
#include <math.h>
#define NOPTIONS 5/*from w ww.  j a  va2s.c  o  m*/

void menu(void);
double sum(double, double);
double difference(double, double);
double power(double, double);
double product(double, double);
double quotient(double, double);

int main(void){
  // declare array of function pointers
  double (*funcs[NOPTIONS])(double, double) = {sum, difference, product, quotient,power};
  double x, y;
  int ch;
  
  while (1){
    menu();
    if ((ch = getchar()) != '\n')
      while (getchar() != '\n') continue;//clear
    ch -= 'a';
    if (ch < 0 || ch > 5){
      puts("This is not a valid option. Try again.");
      continue;
    }
    else if (ch == 5)
      break;
    
    printf("Enter two numbers: ");
    while(scanf("%lf %lf", &x, &y) != 2){
      while (getchar() != '\n') continue;
      printf("Invalid input. Enter two numbers: ");
    }
    while (getchar() != '\n') continue;

    printf("%f\n", funcs[ch](x, y));
    puts("");
  }
  puts("Bye.");
}

void menu(void)
{
  puts("Choose an operation:");
  puts("a) add");
  puts("b) subtract");
  puts("c) multiply");
  puts("d) divide");
  puts("e) power");
  puts("f) quit");
  return;
}

double sum(double x, double y)
{
  return x + y;
}

double difference(double x, double y)
{
  return x - y;
}

double power(double x, double y)
{
  return pow(x, y);
}

double product(double x, double y)
{
  return x * y;
}

double quotient(double x, double y)
{
  return x / y;
}

Result


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