+     add -     subtract *     multiply /     divide %     take remainder of an integer division

Remember:

Arithmetic operators in computer programs must ALWAYS operate on two values of the SAME type!!! The result of the arithmetic operation will ALWAYS have the SAME type as the operands.

• When values of different types are used in an arithmetic operation, the value of the narrow type is AUTOMATICALLY converted to the wider type

• Then the operation is performed on the two value of same type

• Examples:

  2.0 + 3 --> 2.0 + 3.0 = 5.0 (result is double) (int) 2 + (short) 3 --> (int) 2 + (int) 3 = (int) 5

• Pay special attention on the division / operator:
  • floating point division computes quotient and the remainder in decimal places

  • integer division computes the integral quotient.

  Examples:

  7.0 / 4.0 = 1.75 (divide 2 double values, natural) 7 / 4.0 = 1.75 (7 / 4.0 --> 7.0 / 4.0 = 1.75) 7.0 / 4 = 1.75 (7.0 / 4 --> 7.0 / 4.0 = 1.75) 7 / 4 = 1 <- integer division !

• Arithmetic expression in programming languages are evaluated according to strict rules of priority.

• Each operator in a programming language is assigned:
  • a priority level

  • an associativity direction

• The following 2 rules are used in evaluating expressions:
  • Operations involving operators of higher priority are evaluated before lower priority operators.

  • When operators have the same priority, then the expression is evaluated in the direction given by their associativity direction

• Warning: different programming languages may have different priority and associativity rules !

• Priority & Associativity of Arithmetic Operators in C/C++:

  Priority	Operator(s)	Associativity
  1	*   /   %	left -> right
  2	+   -	left -> right

• Some examples:

  6 - 2 * 5	-> 6 - (2 * 5) -> (6 - 10) -> -4
  6 - 2 * 5 - 8 / 3	-> 6 - (2 * 5) - (8 / 3) -> 6 - 10 - 2 [Same priority: use assoc rule !] -> (6 - 10) - 2 -> -4 - 2 -> -6
  6.0 - 8 / 5	-> 6.0 - 8 / 5 -> 6.0 * 1 [double + int: convert !] -> 6.0 * 1.0 -> 6.0
  6.0 * 8 / 5	-> 6.0 * 8.0 / 5 -> 48.0 / 5 [double / int: convert!] -> 48.0 / 5.0 -> 9.6