pset1 - Greedy Errors "error: expected expression"

Question

Please help! I cant solve some errors (from: [http://docs.cs50.net/problems/greedy/greedy.html][1]) running this code:

int main(void) 
{
    float change = 0;
    int coin_used = 0;
    int change2 = 0;
    printf("Change owed:\n");
    change = get_float();

    while (change <= 0)
    {
        printf("Enter a valid number. Change owed:");
        change = get_float();
    }
    change2 = change * 100;

     while (change2 != 0)
    {
        if (change2%25 != change2)   
            change2 %= 25;
            coin_used++;

        else if(change2%10 != change2);   
            change2 %= 10;
            coin_used++;

        else if(change2%5 != change2)   
            change2 %= 5;
            coin_used++;

        else (change2%1 != change2);   
        change2 %= 1;
        coin_used++;  
     }
    printf("Modulo: %i\n", change2);//I momentarily created this to see the output
    printf("change %f\n", change);
    printf("coin used %d\n", coin_used);
    printf("change2 %i\n", change2);
}

And I got this output:

greedy.c:25:9: error: expected expression

    else if(change2%10 != change2);

greedy.c:30:9: error: expected expression

    else if(change2%5 != change2)

greedy.c:35:9: error: expected expression

    else (change2%1 != change2);

Answer 1

The error is created by the compiler finding an else clause without knowing the corresponding if (there has to be exactly one statement or code block in between).

Use {} blocks with your if to conditionally execute several statements, and never ever place a semicolon behind your if condition, that's the empty statement, you essentially tell the compiler to conditionally do nothing, and proceed with the next line.