CODEWITHSUNDEEP
ccs50
tareq91z
tareq91z

Reputation: 13

How to create a function in C that prompts the user for positive integers only and call it in the main function?

This is my code. I failed to use the break keyword after the printf function in order to break out of the loop. When I enter a negative number or zero, it doesn't prompt me again to re-enter.

#include <stdio.h>
#include <cs50.h>

int get_positive_int(void);

int main (void)
{
    get_positive_int();
}


int get_positive_int(void)
{   
  int i;
  i = get_int("Integer: ");

  while (true)
  {
    if (i<1)
    {
       return i;
    }
    else
    {
       printf("%i", i);  
    }
  }
}

Upvotes: 0

Views: 938

Answers (1)

RobertS supports Monica Cellio
RobertS supports Monica Cellio

Reputation: 15042

The algorithm in the function get_positive_int() is wrong:

  1. You need to place i = get_int("Integer: "); inside of the while loop.

  2. Your if condition:

if (i < 1)

is wrong as that would return i if i is a negative integer or 0. If you want to return i when i is a positive integer or 0 you should use if(i >= 0).

  1. Note that you can also place:
if (i == INT_MAX)
{
   // optional error handling.
   return INT_MAX;
}

after the call to maintain the occurrence of a read error. But if you want to only return INT_MAX then, you do not need to do so and can omit it since this would fit to the conditional statement ``if(i >= 0)` and its body.

The code is then:

int get_positive_int(void)
{   
  int i;

  while (true)
  {
    i = get_int("Integer: ");

    if (i == INT_MAX)
    {
        // optional error handling.
        return INT_MAX;
    }
    else if (i >= 0)
    {
       return i;
    }

    printf("%i", i);  
  }
}

Side note: If you don´t want to count 0 as positive integer, you need to have i >= 1 as the condition of the if statement.

As you said in the comments you only want to continue if i is a positive integer and exit if i is a negative characters or 0:

void get_positive_int(void)
{   
  int i;

  while (true)
  {
    i = get_int("Integer: ");

    if (i < 1)
    {
       return;
    }

    printf("%i\n", i);  
  }
}

Note that in this case, the return type of get_positive_int shall be void instead of int and it should omit to return i as it is not necessary to return any value from the function.

Upvotes: 2

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