Increase difficulty based on score

What I'm trying to do is very straightforward and easy, but I am wondering whether there is a more elegant solution.

Basically I have a game and I want the difficulty to increase the moment the score gets between 100 - 500, then increase once again when the score is between 500 - 1500, then again when the score is between 1500 - 3000. In total, the difficulty should increase 3 times.

I need to check:

• Whether I am in one of those ranges.

• Whether I already increased the score when I got in that range.

Here's what I've got.

bool Increased100500 = false;
bool Increased5001500 = false;
bool Increased15003000 = false;

void IncreaseScore()
{
    if (Score >= 100 && Score = 500 && Score = 1500 && !Increased15003000)
    {
        Increase();
        Increased15003000 = true;
    } 
}

LE: I should have mentioned that the method above is called multiple times per frame.

Be careful with your inequalities. You've listed 500 twice: once as if (Score = 500). That's confusing, as the first condition takes precedence.

I think that you would be better off with one state variable representing the current difficulty level. The code would also be simpler if you determine NewDifficulty using a level-triggered rather than edge-triggered mechanism.

int Difficulty;

void IncreaseScore()
{
    int NewDifficulty = (Score <   100) ? 0
                      : (Score <=  500) ? 1
                      : (Score <= 1500) ? 2
                                        : 3;
    // One-way ratchet: difficulty can only increase, even if the
    // score subsequently drops.
    if (NewDifficulty < Difficulty)
    {
        Difficulty = NewDifficulty;
    }
}

If the score can never decrease in this game, then you can simplify it further:

void IncreaseScore()
{
    Difficulty = (Score <   100) ? 0
               : (Score <=  500) ? 1
               : (Score <= 1500) ? 2
                                 : 3;
}

StackExchange Code Review Q#61889, answer score: 19