CODEWITHSUNDEEP
c++cmathmodulus
Ahmad Gaffoor
Ahmad Gaffoor

Reputation: 103

Modulus operator in c

I need to check the divisibility of a number in c. How can I use the modulus operatpr in C to check if a number is divisible by another number? I tried doing this:

if (file_int % 3) {
    printf("Hoppity \n");
}

It didn't work, although file_int is equal to 9.

What did I do wrong?

Thanks

Upvotes: -1

Views: 1667

Answers (5)

Tevo D
Tevo D

Reputation: 3381

The mod operator returns the remainder resulting from the division... since 9 is divisible by three with no remainder, the return would be zero.

However, conditional statements evaluates to true if non-zero, false if zero. You need to change it to (file_int % 3 == 0).

Upvotes: 0

Cavaz
Cavaz

Reputation: 3119

because if it is divisible by 3 file_int % 3 will be equal to 0, and the if block won't execute.

Try

if(file_int % 3 == 0) {
    // do stuff
}

Upvotes: 1

smelch
smelch

Reputation: 2543

If the result of the modulus is 0, it is evenly divisible. It would appear you are looking for it to be not divisible by 3 to continue the loop, though your code snippet is not sufficient to confidently assume your intent.

Upvotes: 1

ildjarn
ildjarn

Reputation: 62975

if (file_int % 3) is the same as if (file_int % 3 != 0), which is the opposite of what you want.

if (file_int % 3 == 0) {
    printf("Hoppity \n");
}
// or
if (!(file_int % 3)) {
    printf("Hoppity \n");
}

Upvotes: 3

Justin Niessner
Justin Niessner

Reputation: 245389

It didn't work because the operation will return 0 which will be treated as false.

You actually need:

if(!(file_int % 3)) {
    printf("Hoppity \n");
}

Upvotes: 7

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