C - while operator in for loop initializer

Question

Why I cannot write smthng like this?

int i, size;
int *arr;
...
for(i = size - 1, while(arr[i] == 0) i--; i >= 0; i--) { ... }

Answer 1

This is just no valid syntax in C.

A Solution for what you want might be:

int i, size;
int *arr;
...
for(i = size - 1; i >= 0; i--) {
    if (arr[i] == 0)
        continue;
    ...
}