with only stdio, count number of occurrences of a substring within a string

countSubstr.c

#include <stdio.h>

int countSubstr(char string[], char substring[])
{
    int count = 0;
    size_t i = -1;
    while(string[++i])
    {
        int match = 1;
        size_t j = 0;
        while (substring[j])
        {
            match &= substring[j] == string[i + j++];
        }
        count += match;
    }
    return count;
}

void test(char name[], int expected, char string[], char substring[]){
    int actual = countSubstr(string, substring);
    char* status = (actual == expected)? "PASS" : "FAIL";
    printf("%s: %s\nActual: %d\nExpected: %d\n\n",name,status,actual,expected);
}


int main(void) {
    test("Two empty strings", 0, "", "");
    test("Empty substring", 19, "sub str sub str sub", "");
    test("Empty string", 0, "", "sub");
    test("Case 1", 4, "dbdbsnasdb dbdxx", "db");
    test("Case 2", 3, "dbdbsnasmfdb", "db");
    test("No match", 0, "dbdbsnasmfdb", "dxb");
    test("Inner matching", 3, "abababa", "aba");
    test("Identity test", 1, "a", "a");
    test("Longer substring", 0, "a", "abcd");
	return 0;
}