The decrement operator has the form -- and subtracts 1 from the variable.
Assuming the variables are of type int, the following three statements all have exactly the same effect:
count = count - 1; count -= 1; --count;
They each decrement the variable count by 1.
Suppose count has the value 10 in the following statement:
total = --count + 6;
The variable total will be assigned the value 15 from 9 + 6.
The variable count, with the initial value of 10, has 1 subtracted from it before it is used in the expression so that its value will be 9.
For count--, the decrementing of count occurs after its value has been used.
Suppose count has the value 5 in this statement:
total = --count + 6;
total will be assigned the value 10 (from 4 + 6). In this statement:
total = 6 + count-- ;
total will be assigned the value 11 (from 6 + 5).
Both the increment and decrement operators can only be applied to integer types and character codes.