CODEWITHSUNDEEP
cintegerdivision
hicksi
hicksi

Reputation: 43

C integer and float division output

Can somebody explain the output of the following code: http://cpp.sh/9dy44

Why is the last line always 0.17?

float a = 17, b = 100;

printf("%f\n", 17/100);
printf("%f\n", a/b);
printf("%f\n", 17/b);
printf("%f\n", 17.0f/b);
printf("%f\n", a/100);
printf("%f\n", a/100.0f);
printf("%f\n", 5/100);

output

0.000000
0.170000
0.170000
0.170000
0.170000
0.170000
0.170000

Upvotes: 0

Views: 1577

Answers (2)

Usama
Usama

Reputation: 336

Because You are dividing integers and than trying to print (the integer result as) a float value

Try This

// Example program
#include <stdio.h>

int main()
{
    float a = 17, b = 100;

    printf("%f\n", 17.0/100);
    printf("%f\n", a/b);
    printf("%f\n", 17/b);
    printf("%f\n", 17.0f/b);
    printf("%f\n", a/100);
    printf("%f\n", a/100.0f);
    printf("%f\n", 5.00/100);

    return 0;
}

Upvotes: 0

sagi
sagi

Reputation: 40491

This is called Undefined Behaviour , don't try to understand why this is happening , because as the name suggests , it is undefined !. The undefined behaviour happens because you are trying to print a double but you're passing two integers . Note that you are also getting a warning :

14:25: warning: format '%f' expects argument of type 'double', but argument 2 has type 'int' [-Wformat=]

Change last line to this:

    printf("%f\n", 5.0/100);

And it will work as expected .

Upvotes: 2

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