Easiest way to flip a boolean value?

Question

I just want to flip a boolean based on what it already is. If it\'s true - make it false. If it\'s false - make it true.

Here is my code excerpt:

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Answer 1

Just because my favorite odd ball way to toggle a bool is not listed...

bool x = true;
x = x == false;

works too. :)

(yes the x = !x; is clearer and easier to read)

Answer 2

Easiest solution that I found:

x ^= true;

Answer 3

If you know the values are 0 or 1, you could do flipval ^= 1.

Answer 4

For integers with values of 0 and 1 you can try:

value = abs(value - 1);

MWE in C:

#include <stdio.h>
#include <stdlib.h>
int main()
{
        printf("Hello, World!\n");
        int value = 0;
        int i;
        for (i=0; i<10; i++)
        {
                value = abs(value -1);
                printf("%d\n", value);
        }
        return 0;
}

Answer 5

The codegolf'ish solution would be more like:

flipVal = (wParam == VK_F11) ? !flipVal : flipVal;
otherVal = (wParam == VK_F12) ? !otherVal : otherVal;

Answer 6

Just for information - if instead of an integer your required field is a single bit within a larger type, use the 'xor' operator instead:

int flags;

int flag_a = 0x01;
int flag_b = 0x02;
int flag_c = 0x04;

/* I want to flip 'flag_b' without touching 'flag_a' or 'flag_c' */
flags ^= flag_b;

/* I want to set 'flag_b' */
flags |= flag_b;

/* I want to clear (or 'reset') 'flag_b' */
flags &= ~flag_b;

/* I want to test 'flag_b' */
bool b_is_set = (flags & flag_b) != 0;