Is it better to check if a variable already has that value before assigning it?-CodePudding

I'm sorry if it sounds like a stupid question, but: let's say that I have to change the bool variable 'a', based on a condition 'cond', but it could happens that 'a' already has the value I want to assign to it.

Now, should I do something like this:

// something that changes 'a'

if (cond) {
    a = true;
}

or should I check before if the variable 'a' is already true, like this:

// something that changes 'a'

if (cond) {
    if (!a) {
         a = true;
    }
}

Which way is faster? (and if there are differences in different programming languages)

CodePudding user response：

Use whatever is most clear to express your code's intent, which is usually the direct a = true;. A good compiler will optimize a boolean if (!a) { a = true; } into a = true; so the same performance can be expected.

Avoid premature optimization.