for loop - statement with no effect

For some reason I'm getting an 开发者_运维问答error: statement with no effect on this statement.

for (j = idx; j < iter; j + increment) {
    printf("from loop idx = %i", (int)idx);
    punc(ctxt, j);
}

You probably meant to write j += increment instead of j + increment.

I think you meant j += increment, as j + increment doesn't actually alter j or indeed have any side effects at all - it is a statement with no effect, which is what the compiler is telling you

Replace

j + increment

With

j += increment

You are getting that as an error? How cool, I wish my compiler did that. Basically j + increment will return the sum of those two, but j won't get modified so your loop would probably run forever.

It's clear you meant +=, but in the case that isn't true, the 'volatile' qualifier should prevent warnings.