A Crash Course in C - copyright 1995 by Anand Mehta - Basic Operators

Some basic operators are

• expression operators
  • ( )
• unary operators
  • !, ~, ++, --, +, -
  • !: negation
    • !(0) ==> 1
    • !(any non-zero value) ==> 0
  • ++/--: increment/decrement by 1
    • prefix: increments the variable and gives the new value as the result
    • postfix: gives the old value as the result and then increments the variable
• arithmetic operators
  • *, / , %
  • % is called modulus division (remainder)
  • +, -
• bitwise shift operators
  • <<, >>
• comparison operators
  • the logical operators return a 1 (true) or 0 (false)
  • for any conditional test, any non-zero value is true and a 0 is false
  • <,>, <=, >=
  • ==, !=
  • == is the equality comparision (not assignment =)
    • A common error is using the assignment operator = when the logical operator == is required, e.g. (x = 2) instead of (x == 2); both are valid expressions, so the compiler will not indicate an error.
• bitwise operators
  • & - and
  • ^ - exclusive or
  • | - or
• logical operators
  • &&, ||
  • logical operators are evaluated until an expression is known to be true or false
• conditional, compact if-else as an expression instead of a statement
  • ? :
• assignment operators
  • =, +=, -=, *=, /=, %= !
  • op= assignment, E1 op= E2 <==> E1 = E1 op E2, with E1 evaluated once
  • for example, x+=2 <==>x=x+2
• , (comma)
  • combines separate expressions into one
  • evaluates them from left to right
  • the value of the whole expression is the value of the right most sub-expression

Next slide