Setting a bit
Use the bitwise OR operator (|
) to set a bit.
number |= 1UL << n;
That will set the n
th bit of number
. n
should be zero, if you want to set the 1
st bit and so on upto n-1
, if you want to set the n
th bit.
Use 1ULL
if number
is wider than unsigned long
; promotion of 1UL << n
doesn't happen until after evaluating 1UL << n
where it's undefined behaviour to shift by more than the width of a long
. The same applies to all the rest of the examples.
Clearing a bit
Use the bitwise AND operator (&
) to clear a bit.
number &= ~(1UL << n);
That will clear the n
th bit of number
. You must invert the bit string with the bitwise NOT operator (~
), then AND it.
Toggling a bit
The XOR operator (^
) can be used to toggle a bit.
number ^= 1UL << n;
That will toggle the n
th bit of number
.
Checking a bit
You didn't ask for this, but I might as well add it.
To check a bit, shift the number n to the right, then bitwise AND it:
bit = (number >> n) & 1U;
That will put the value of the n
th bit of number
into the variable bit
.
Changing the nth bit to x
Setting the n
th bit to either 1
or 0
can be achieved with the following on a 2's complement C++ implementation:
number ^= (-x ^ number) & (1UL << n);
Bit n
will be set if x
is 1
, and cleared if x
is 0
. If x
has some other value, you get garbage. x = !!x
will booleanize it to 0 or 1.
To make this independent of 2's complement negation behaviour (where -1
has all bits set, unlike on a 1's complement or sign/magnitude C++ implementation), use unsigned negation.
number ^= (-(unsigned long)x ^ number) & (1UL << n);
or
unsigned long newbit = !!x; // Also booleanize to force 0 or 1
number ^= (-newbit ^ number) & (1UL << n);
It's generally a good idea to use unsigned types for portable bit manipulation.
or
number = (number & ~(1UL << n)) | (x << n);
(number & ~(1UL << n))
will clear the n
th bit and (x << n)
will set the n
th bit to x
.
It's also generally a good idea to not to copy/paste code in general and so many people use preprocessor macros (like the community wiki answer further down) or some sort of encapsulation.
Yes, it's in the Debugging section of the properties page of the project.
In Visual Studio since 2008: right-click the project, choose Properties, go to the Debugging section -- there is a box for "Command Arguments". (Tip: not solution, but project).
Best Answer
Ben had a good start to the question along with the help of Tymek, but you need to go to the next step. Once you have added your icon to your resources, you will also need a resource file
.rc
in order to set the icon as the main icon of your application.If you don't know if you already have a resource file, open your Resource View for the project: go to View->Resource View or Ctrl+Shift+E (in Visual Studio 2012/2013 View->Other Windows->Resource View or you can type Ctrl+W,R to get it to open and in 2015 Ctrl+Shift+E). Check to see if you have a MyProject->MyProject.rc. This is where you should
Add
your icon. It should then create a resource file for you.Now Ctrl+Shift+F to search the whole solution. Search for your icon filename so that you can open the actual
.rc
file. When you do so it may suggest that you already have it open just accept.Now find a place to add the following line to the
.rc
file:MAINICON ICON "foo.ico"
The next time you compile you can browse to the folder with the executable and see that you have the icon associated with the app and when you run it from there it will use the icon.
Note:
.ico
file. You cannot use a PNG image file for your executable's icon, it will not work. You must use.ico
. There are web utilities that convert images to .ico files. as quoted from bobobobo.