6.1 Basic Arithmetic

Basic arithmetic in C is done with the usual binary operators of algebra: addition (‘+’), subtraction (‘-’), multiplication (‘*’) and division (‘/’). The unary operator ‘-’ is used to change the sign of a number. The unary + operator also exists; it yields its operand unaltered.

‘/’ is the division operator, but dividing integers may not give the result you expect. Its value is an integer, which is not equal to the mathematical quotient when that is a fraction. Use ‘%’ to get the corresponding integer remainder when necessary. See Division and Remainder. Floating point division yields value as close as possible to the mathematical quotient.

These operators use algebraic syntax with the usual algebraic precedence rule (see Binary Operator Grammar) that multiplication and division are done before addition and subtraction, but you can use parentheses to explicitly specify how the operators nest. They are left-associative (see Associativity and Ordering). Thus,

-a + b - c + d * e / f

is equivalent to

(((-a) + b) - c) + ((d * e) / f)