如何在C中设置位

Question

There's a variable:

char segment = 0;

After 1 or with bit 15, segment = 1;

Just means this bit check already.

Question is how to cancel the mark of bit 15 (set back to 0)?

Use "~"?

Answer 1

Following program sets bit, clears bit and toggles bit

#include<stdio.h>

void main(void)
{
unsigned int byte;
unsigned int bit_position;
unsigned int tempbyte = 0x01;
//get the values of the byte and the bit positions 
//set bit
byte = (byte | (tempbyte << bit_position));// set the bit at the position given by bit_position
//clear bit
byte = (byte & ~(tempbyte << bit_position));//clear the bit at the position given by bit_position
//toggle bits
byte = (byte ^ (tempbyte << bit_position));//toggle the bit at the position given by bit_position
}

Answer 2

To get rid of the MSB of an 8-bit character for example, you can AND with 0x7F

eg segment = segment & 0x7F;

To dynamically produce the mask, you can use bit shifting operations (ie the << operator).