Do addition, subtraction, multiplication, or division based on menu selection - C Operator

C examples for Operator:Arithmetic Operator

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Description

Do addition, subtraction, multiplication, or division based on menu selection

Demo Code

#include <stdio.h>
#include <ctype.h>

int get_first(void);
void print_menu(void);
float get_number(void);

int main(void)
{
  int operation;/*from  w  ww  .  j a  va2 s .c o  m*/
  float num1, num2;

  print_menu();
  while ((operation = get_first()) != 'q')
  {
    printf("Enter first number: ");
    num1 = get_number();
    printf("Enter second number: ");
    num2 = get_number();

    switch (operation)
    {
      case ('a') :
        printf("%.3f + %.3f = %.3f\n", num1, num2, num1 + num2);
        break;
      case ('s') :
        printf("%.3f - %.3f = %.3f\n", num1, num2, num1 - num2);
        break;
      case ('m') :
        printf("%.3f * %.3f = %.3f\n", num1, num2, num1 * num2);
        break;
      case ('d') :
        while (num2 == 0)
        {
          printf("Enter a number other than 0: ");
          num2 = get_number();
        }
        printf("%.3f / %.3f = %.3f\n", num1, num2, num1 / num2);
        break;
      default :
        printf("I do not recognize that input. Try again.");
    }
    print_menu();
  }
}

int get_first(void){
  // return first non-whitespace character
  int ch;

  do ch = getchar(); while (isspace(ch));

  while (getchar() != '\n')
    ;

  return ch;
}


void print_menu(void)
{
  printf("Enter the operation of your choice:\n");
  printf("a. add            s. subtract\n");
  printf("m. multiply       d. divide\n");
  printf("q. quit\n");
}

float get_number(void)
{
  int ch;
  float num;

  while (scanf("%f", &num) != 1)
  {
    while ((ch = getchar()) != '\n') // echo user input and clear stream
      putchar(ch);

    printf(" is not a number.\n");
    printf("Please enter a number, such as 2.5, -1.78E8, or 3: ");
  }

  return num;
}

Result


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