Balancing

Many binary operators (i.e. operators which work on two operands), require the operands to be converted to a common type before the operation is performed. This common type is also the type of the result. For example if an int is added to a long int, the int is first converted to a long int. If an int is added to an unsigned int, the int is first converted to an unsigned int.

This process of arriving at a common type is known as balancing or, in the terminology of the ISO-C Standard, the usual arithmetic conversions. Usually the conversions involve one operand being converted to that of the other; but occasionally the type of both operands must be changed. Sometimes we refer to an operand being promoted to the type of the other; don't confuse this process with integral promotion.

Balancing is performed according to the following set of rules:

• If either operand is long double, the other operand is converted to long double.
• Otherwise, if either operand is double, the other is converted to double.
• Otherwise, if either operand is float, the other is converted to float.
• Otherwise:
• The integral promotions are performed on both operands
• If either operand is unsigned long int the other is converted to unsigned long int
• Otherwise if one operand is long int, and the other operand is unsigned int:
• If a long int can represent all values of an unsigned int, the unsigned int is converted to long int.
• Otherwise both are converted to unsigned long int
• Otherwise if one operand is long int the other is converted to long int
• Otherwise if either operand is unsigned int the other is converted to unsigned int.
• Otherwise, both operands have type int

See the following table:

Index