Documentation

The value of the expression that includes the given operation is the value of the left operand after assignment.

Assigning the y value to the x variable                   y = x;

The following operations unite arithmetic or bitwise operations with operation of assignment:

Adding x to the y variable                               y += x;
Subtracting x from the y variable                        y -= x;
Multiplying the y variable by x                          y *= x;
Dividing the y variable by x                             y /= x;
Module x value of y                                      y %= x;
Logical shift of y representation to the right by x bit  y >>= x;
Logical shift of y representation to the left by x bit   y <<= x;
Bitwise operation AND                                    y &= x;
Bitwise operation OR                                     y |= x;
Bitwise operation exclusive OR
of x and y binary notations                              y ^= x;

There can be only one operation of assignment in an expression. Bitwise operations are performed with integer numbers only. The logical shift operation uses values of x less than 5 binary digits. The greater digits are rejected, so the shift is for the range of 0 to 31 bit. By %= operation (y value by module of x), the result sign is equal to the sign of divided number.