The -- (decrement) operator subtracts 1 from the value of a scalar operand, or if the operand is a pointer, decreases the operand by the size of the object to which it points. The operand receives the result of the decrement operation. The operand must be a modifiable lvalue.
You can put the -- before or after the operand. If it appears before the operand, the operand is decremented, and the decremented value is used in the expression. If the -- appears after the operand, the current value of the operand is used in the expression and the operand is decremented.
For example:
play = --play1 + play2--;is similar to the following expressions; play2 is altered before play:
int temp, temp1, temp2;
temp1 = play1 - 1;
temp2 = play2;
play1 = temp1;
temp = temp1 + temp2;
play2 = play2 - 1;
play = temp;The result has the same type as the operand after integral promotion, but is not an lvalue.
The usual arithmetic conversions are performed on the operand.