Operators

Unary operators

    sizeof(i)       the number of bytes of storage allocated to i 
    +1              positive 1  
    -1              negative 1  
    ~i              one's complement (bitwise complement)
    !i              logical negation (i.e., 1 if i is zero, 0 otherwise)
    *i              returns the value stored at the address pointed to by i
    &i              returns the address in memory of i
    ++i             adds one to i, and returns the new value of i
    --i             subtracts one from i, and returns the new value of i
    i++             adds one to i, and returns the old value of i
    i--             subtracts one from i, and returns the old value of i
    i[j]            array indexing 
    i(j)            calling the function i with argument j
    i.j             returns member j of structure i
    i->j            returns member j of structure pointed to by i
    a,b             evaluate both a and b, return the value of b

Binary operators

    +          addition
    -          subtraction
    *          multiplication
    /          division
    %          remainder  
    %          modulo
    <<         left-shift 
    >>         right-shift
    &          bitwise AND
    |          bitwise OR
    ^          bitwise exclusive-OR
    &&         logical AND 
    ||         logical OR 
    <          less than 
    >          greater
    >          than
    <=         less than or equal     
    >=         greater than or equal       
    ==         equals 
    !=         does not equal

• C has no keywords as true or false. They are non-zero or zero values, usually 1 or 0.
• `OR', `AND' , and `NOT': differences between bitwise and logical operators.

Assignment operators

    =      assignment
    +=     addition assignment
    -=     subtraction assignment
    *=     multiplication assignment
    /=     division assignment
    %=     remainder/modulus assignment
    &=     bitwise AND assignment
    |=     bitwise OR assignment
    ^=     bitwise exclusive OR assignment
    <<=    left shift assignment
    >>=    right shift assignment

• Assignment operators takes the value on the right and places it into the variable on the left.
• C provides more derivatives by combining computation and assignment together
• Note the difference between assignment and equal operators. Don't make the mistake of using '=' when you meant '=='!

Precedence and Associativity

    Operator                                   Associativity
    --------                                   -------------

    () [] ->> .                                left-to-right
    - + ++ -- ! ~ * & sizeof (type)            right-to-left
    * / %                                      left-to-right
    + -                                        left-to-right
    << >>                                      left-to-right
    < <= > >=                                  left-to-right
    == !=                                      left-to-right
    &                                          left-to-right
    ^                                          left-to-right
    |                                          left-to-right
    &&                                         left-to-right
    ||                                         left-to-right
    ?:                                         right-to-left
    = += -= *= /= %= &= ^= |= <<= >>=          right-to-left
    ,                                          left-to-right

• Precedence: The order in which operators are applied in expressions.
• Associativity: The order in which expressions involving operators of the same precedence are evaluated.
• Use parentheses to specify a different order of evaluation. It is recommended to use parentheses for clear and easy to read programs. But you still need to be prepared for the complexity in general.

Samples:

   int a, b, c;
   a = 2, b = 1;
   c = 1 + a - -- b;
   c = 1 + a - b -- ;
   c = 1 + a - ++ b;
   c = 1 + a - b ++ ;
   c = (1 + a, b);
   c = 1 + (a, b);