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   switch wParam     case VK F11    if  flipVal    true         flipVal   false      else       flipVal   true      break   case VK F12    if  otherVal    true         otherValVal   false      else       otherVal   true      break   default  break

User · Answer

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;
}

User · Answer

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  amp    flag b      I want to test  flag b     bool b is set    flags  amp  flag b     0

User · Answer

I prefer John T s solution  but if you want to go all code-golfy  your statement logically reduces to this     if key is down  toggle the boolean  else leave it alone  flipVal     wParam  VK F11   amp  amp   flipVal        wParam  VK F11   amp  amp  flipVal   if wParam  VK F11  Break     if key is down  toggle the boolean  else leave it alone  otherVal     wParam  VK F12   amp  amp   otherVal        wParam  VK F12   amp  amp  otherVal   if wParam  VK F12  Break

User · Answer

If you know the values are 0 or 1  you could do flipval    1

User · Answer

flipVal    1    same goes for   otherVal

User · Answer

Clearly you need a factory pattern    KeyFactory keyFactory   new KeyFactory    KeyObj keyObj   keyFactory getKeyObj wParam   keyObj doStuff      class VK F11 extends KeyObj      boolean val     public void doStuff           val    val          class VK F12 extends KeyObj      boolean val     public void doStuff           val    val          class KeyFactory      public KeyObj getKeyObj int param          switch param             case VK F11              return new VK F11             case VK F12              return new VK F12                  throw new KeyNotFoundException  Key     param     was not found               D   lt  sarcasm gt

User · Answer

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

User · Answer

This seems to be a free-for-all     Heh  Here s another varation  which I guess is more in the category  clever  than something I d recommend for production code   flipVal     wParam    VK F11   otherVal     wParam    VK F12     I guess it s advantages are    Very terse Does not require branching   And a just as obvious disadvantage is   Very terse   This is close to  korona s solution using    but taken one  small  step further

User · Answer

You can flip a value like so   myVal    myVal    so your code would shorten down to   switch wParam        case VK F11      flipVal    flipVal      break       case VK F12      otherVal    otherVal      break       default      break

User · Answer

Just because I like to question code  I propose that you can also make use of the ternary by doing something like this   Example   bool flipValue   false  bool bShouldFlip   true  flipValue   bShouldFlip    flipValue   flipValue

User · Answer

The codegolf ish solution would be more like   flipVal    wParam    VK F11     flipVal   flipVal  otherVal    wParam    VK F12     otherVal   otherVal

User · Answer

Easiest solution that I found   x    true

User · Answer

Clearly you need a flexible solution that can support types masquerading as boolean  The following allows for that   template lt typename T gt     bool Flip const T amp  t     You can then specialize this for different types that might pretend to be boolean  For example   template lt  gt   bool Flip lt bool gt  const bool amp  b     return  b    template lt  gt   bool Flip lt int gt  const int amp  i       return   i    0       An example of using this construct   if Flip false      printf  flipped false n      if  Flip true      printf  flipped true n       if Flip 0      printf  flipped 0 n      if  Flip 1     printf  flipped 1 n        No  I m not serious

[c++] Easiest way to flip a boolean value?

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