不应使用按位运算符代替逻辑运算符

Question

//  How does this program work with ternary operator
#include <stdio.h>   
int main()
{
    int x = 2, y = 5;
    (x &  y) ? printf("True ") : printf("False "); // How do we get output
    (x && y) ? printf("True ") : printf("False ");
    return 0;
}

How does this program work? How do the logical and bitwise operators work?

Answer 1

In this program & is a bitwise operator which will do bitwise and operation on 2 and 5.

0000 0010<=2
0000 0101<=5
0000 0000<=output

So the first line will print False , whereas second one is normal and operator for which both values are true(non zero numbers ) so 2 && 5 will result in true and the output will be True .

Answer 2

The bitwise AND operator is a single ampersand: &. A handy mnemonic is that the small version of the boolean AND, &&, works on smaller pieces (bits instead of bytes, chars, integers, etc). In essence, a binary AND simply takes the logical AND of the bits in each position of a number in binary form.

Example for & ( and ):

00000010 & //2
00000101 = //5
--------
00000000   // 0

Bitwise OR works almost exactly the same way as bitwise AND. The only difference is that only one of the two bits needs to be a 1 for that position's bit in the result to be 1. (If both bits are a 1, the result will also have a 1 in that position.) The symbol is a pipe: |. Again, this is similar to boolean logical operator, which is ||.

Example for | ( OR ):

00000010 | //2
00000101 = //5
--------
00000111 //7

There is no boolean operator counterpart to bitwise exclusive-or, but there is a simple explanation. The exclusive-or operation takes two inputs and returns a 1 if either one or the other of the inputs is a 1, but not if both are. That is, if both inputs are 1 or both inputs are 0, it returns 0. Bitwise exclusive-or, with the operator of a caret, ^, performs the exclusive-or operation on each pair of bits. Exclusive-or is commonly abbreviated XOR.

Example for ^ ( XOR ):

00000010 ^ //2
00000101 = //5
--------
00000111 //7

If you get into a bitwise operators I suggest you get a pen and paper, imagine 2 random 8 bit numbers and work them all up on paper(all bitwise operations). Then you can find a Programmer calculator and check out your result.