Define a Macro to set Nth bit to Zero in C

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mahmoud2506

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2022-05-04

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Define a Macro to set Nth bit to Zero in C

Macro definition:

 #define SETPIN(PIN,N) (PIN &= ~(1<<N))

Here,

SETPIN is the Macro name
PIN is the value whose bit to set to zero
N is the bit number

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mahmoud2506

2022-05-04

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Example:

#include <stdio.h>

#define SETPIN(PIN,N) (PIN &= ~(1<<N))

int main(){
	
	unsigned char val = 0xFF;
	unsigned char bit = 2;
	
	printf("val = %X\n",val);
	
	//SET bit number 2 to zero 
	SETPIN(val,bit);
	printf("Aftre setting  bit %d to zero, val = %X\n", bit, val);
	
	return 0;	
}

Output

    val = FF
    Aftre setting  bit 2 to zero, val = FB

Explanation:

In this example, initially the value of val is 0xFF that is "1111 1111" in binary.
To set bit number 2 (i.e. third bit) to zero, when we call macro SETPIN(val, bit), the bit number 2 will set to 0. Thus, the output will be "1111 1011" i.e. 0xFB in Hexadecimal.

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