C++ Bit Manipulation Bit Manipulation Application: Small to Capital Letter
Example
One of several applications of bit manipulation is converting a letter from small to capital or vice versa by choosing a mask and a proper bit operation. For example, the a letter has this binary representation 01(1)00001 while its capital counterpart has 01(0)00001. They differ solely in the bit in parenthesis. In this case, converting the a letter from small to capital is basically setting the bit in parenthesis to one. To do so, we do the following:
/****************************************
convert small letter to captial letter.
========================================
a: 01100001
mask: 11011111 <-- (0xDF) 11(0)11111
:---------
a&mask: 01000001 <-- A letter
*****************************************/
The code for converting a letter to A letter is
#include <cstdio>
int main()
{
char op1 = 'a'; // "a" letter (i.e. small case)
int mask = 0xDF; // choosing a proper mask
printf("a (AND) mask = A\n");
printf("%c & 0xDF = %c\n", op1, op1 & mask);
return 0;
}
The result is
$ g++ main.cpp -o test1
$ ./test1
a (AND) mask = A
a & 0xDF = A
