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Using Constants

I define a constant, ALIEN_POINTS, to represent the point value of an alien.

const int ALIEN_POINTS = 150;

I simply use the keyword const to modify the definition. Now I can use ALIEN_POINTS just like any integer literal. Also, notice that the name I chose for the constant is in all capital letters. This is just a convention, but it’s a common one. An identifier in all caps tells a programmer that it represents a constant value.

Next I put the constant to use in the following line:‌

int score = aliensKilled * ALIEN_POINTS;

I calculate a player’s score by multiplying the number of aliens killed by the point value of an alien. Using a constant here makes the line of code quite clear.

Tra p

You can’t assign a new value to a constant. If you try, you’ll generate a compile error.

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