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I am trying to implement my own use of bit flags in C/C++. I have three functions: getBool, setBool, and printBools. All of my current code except one part: I can't set bits to false. They set to true just fine, they read back just fine, but I can't set true bits to false. Here is my code:

#include <iostream>

#define uint unsigned int
#define BIT1 1
#define BIT2 2
#define BIT3 4
#define BIT4 8
#define TRUE 1
#define true 1
#define FALSE 0
#define false 0

int getBool(uint boolSet, uint bit){
    return ((boolSet&bit)==bit);
}

void setBool(uint &boolSet, uint bit, short tf){
    if(getBool(boolSet, bit)) return;
    else if(tf == 1) boolSet += bit;
    else if(tf == 0) boolSet -= bit;
}

void printBools(uint boolSet, uint j){
    uint i = 1, count = 1;
    while(count <= j){
        std::cout<<"Bool "<<count<<": "<<getBool(boolSet, i)<<std::endl;
        i*=2;
        count++;
    }
}

int main(){
    uint boolSet = 0;
    printBools(boolSet, 4); //make sure bits are false
    setBool(boolSet, BIT1, 1); //set bit 1 to true
    setBool(boolSet, BIT3, 1); //set bit 3 to true
    printBools(boolSet, 4); //check set bits
    setBool(boolSet, BIT3, 0); //set bit 3 to false
    setBool(boolSet, BIT4, 1); //set bit 4 to true
    printBools(boolSet, 4); //check set bits
}

Additionally, if you would like to see the output really quickly, here is a link: cpp.sh/6gpu Thank you for your help!

viraptor
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DarkSun
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1 Answers1

2

You return if the bit is set:

if(getBool(boolSet, bit)) return;

so you can never unset them.

(but in practice it's better to either use bitset, or masking with | and & - saves you the checking step)

viraptor
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