Is it OK to use correct++ instead of correct += 1?

It depends on how you use them.

When you use them as a complete statement in themselves, they do the same thing. But if you were to use them in a formula, assignment, or function call, they would be different.

When placed after the variable name, the ++ operator is known as the "post-increment operator". That means it increments the value after determining what to return. For example, let's say you have a function named "print" that will show a value on the screen. Here's what would happen if you used it on each of these:

var score = 4;
print(score += 1);  // this would print "5"
// score is 5 here

var score = 4;
print(score++);    // this would print "4"
// score is 5 here also

Well, when using "variable++", you increment the value by one. But if you use the "variable += [someValue]", you increment the value by any value you'd like. Maybe now you want to increment the variable by only one, but what if later on you decide, that you need to increment with a higher value? Then you have to search for your "variable++" line, and fix it, while if you have the "variable += [otherVariable]", you just change the "otherVariable" and you are done.