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coperatorssemanticsbit-shiftlogical-operators

Meaning of <<= and |=

What is the meaning of <<= and |= in C?

I recognise << is bitshift etc. but I don't know what these are in combination.

Solution

  • Just as x += 5 means x = x + 5, so does x <<= 5 mean x = x << 5.

    Same goes for |. This is a bitwise or, so x |= 8 would mean x = x | 8.

    Here is an example to clarify:

    int x = 1;
x <<= 2;         // x = x << 2;
printf("%d", x); // prints 4 (0b001 becomes 0b100)

int y = 15;
y |= 8;          // y = y | 8;
printf("%d", y); // prints 15, since (0b1111 | 0b1000 is 0b1111)