[Solved] What is the difference between = and |= in C? [closed]

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Do the two lines have same effect of writing one to data register B ?

No.

DDRB = 0b00000001;

writes one to bit-0 and zero to bits 1 to 7, while:

DDRB |= 0b00000001;

is a read-modify-write operation equivalent to:

DDRB = DDRB | 0b00000001;

so it writes a one to bit-0 as before and leaves all other bits unchanged.

So for example if DDRB‘s current value were 0b11110000 after:

DDRB = 0b00000001;

it will be 0b00000001 while after:

DDRB |= 0b00000001;

it will be 0b11110001.

So one sets DDRB to 1, while the other sets DDRB:Bit-0 to 1.

solved What is the difference between = and |= in C? [closed]