My program outputs wrong value and unknown error

Question

It's problem that I'm trying to solve for my beginner programming class. I need to enter change and calculate how many coins I need to give back.

this is my code:

int main(void)
{    
    //prompts user for amount of change and check the value of the imput
    int n = get_float("enter change owned: ");
    
    //converts to p.
    int change = n * 100; 
    
    if (change > 0)
    {
        printf("total change is: %ip\n" , change ); 
    } 
    else
    {
        printf(" ERROR: change given needs to be positive value!\n");
    }
    while(n < 0); 
    int i = 0;
    
    //calculate quarters
    while (change >= 250) 
    {
        n = change - 250;
        i++;     
    }
    
    //calculate dimes
    while (change >= 100) 
    {
        n = change - 100;
        i++;     
    }
    //calculate nickels
    while (change >= 50) 
    {
        n = change - 50;
        i++;     
    }
    //calculate pennies
    while (change >= 1) 
    {
        n = change - 1;
        i++;     
    }
    printf("%d\n", i);    
}

I don't understand why when I enter n = 2.50 and program needs to calculate change as n = n * 100 it outputs result as 200 :S. also my program compiles but then when I run it I get following msg: runtime error: signed integer overflow: 2147483647 + 1 cannot be represented in type 'int'

You do not update the change variable, so your loop are infinite. — user1531591
– user1531591, Commented Aug 16, 2019 at 10:48

Vytautas Plečkaitis · Accepted Answer · 2019-08-16 10:18:44Z

2

int n = get_float("enter change owned: ");

it casts float as integer, so 2.4 becomes 2. Change to :

float n = get_float("enter change owned: ");

also you might want to check this line :

printf("total change is: %ip\n" , change );

to print out integer i would recommend :

printf("total change is: %d\n" , change );

edited Aug 16, 2019 at 10:18

answered Aug 16, 2019 at 10:08

Vytautas Plečkaitis

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