C modulus operator for negative numbers

we_are_the_mods.c

#include <stdio.h>
#include <assert.h>

int modulo(int dividend, int divisor)
{
    int remainder = dividend % divisor;

	if(remainder < 0) {
		return remainder + divisor;
	}

	return remainder;
}


void test_non_symmetric_cycle()
{
	printf("test: \"numbers are non symmetric about 0\"\n");

	assert( modulo( 10, 3) == 1 );
	assert( modulo(  7, 3) == 1 );
	assert( modulo(  4, 3) == 1 );
	assert( modulo(  3, 3) == 0 );
	assert( modulo(  2, 3) == 2 );
	assert( modulo(  1, 3) == 1 );
	assert( modulo(  0, 3) == 0 );
	assert( modulo( -1, 3) == 2 );
	assert( modulo( -2, 3) == 1 );
	assert( modulo( -3, 3) == 0 );
	assert( modulo( -4, 3) == 2 );
	assert( modulo( -7, 3) == 2 );
	assert( modulo(-10, 3) == 2 );
}


int main(int argc, char **argv)
{
	test_non_symmetric_cycle ( );
}