Extra increment within for loop c++

Question

Is the following code safe and defined in the standard? Will 'i' be incremented by 2 if 'condition' is true?

for (size_t i = 0; i < 100; i++) {
    do_something;
    if (condition)
        i++;
}

Answer 1

Of course. There is nothing wrong with it - syntactically. You can even do something like this:

int i = 0;
for (;;) {
    if (i >= 100) {

      break;
    }
    ++i;
}

This code is equivalent to

int i = 0;
while(true) {
    if (i >= 100) {
        break;
    }
    ++i;
}

And furthermore - you can place practically any valid code into the for statement. E.g.

for (do_something_begin(); some_condition(); do_something_end()) {
     CODE;
}

and what compiler does with this code is something like this:

do_something_begin()
while (some_condition()) {
    CODE;
    do_something_end();
}