C: what is the result of I and ^ operation on char?

Question

There is a piece of code:

int p(char *a, char*b)
{
  while (*a | *b) 
  {
   if (*a ^ *b)
    //...
  }
}

and I don't really know what it's doing.

Edit: I understand what the | and ^ operators do, I just don't know what they'll do with char values.

Answer 1

While the string a or string b have not run out of characters, check to see if they are different.

int p(char *a, char*b)
{
     // While both string a and string b have characters left
     // note this assumes they are both zero terminated
     // and if not the same length they have trail zeros
     while (*a|*b)  
     {
         // check to see if the character is different
         // this is done via the xor
         if (*a^*b)
              //(...)
         }

         // should increment pointers or will never exit the loop
         // a++;
         // b++;
      }

Answer 2

That's the XOR operator, which means "exclusive OR". It operates bitwise.

for each bit in your item:

0 ^ 0 = 0
0 ^ 1 = 1
1 ^ 0 = 1
1 ^ 1 = 0

Answer 3

| is the bitwise OR operator. ^ is the bitwise XOR operator:

    10101010      11010101  
  | 01010100    ^ 11111110
  ==========    ==========
    11111110      00101011

While char can be used to represent characters, it's inherently an integer data type. It stores a binary number (just like everything else in a binary digital computer).

Answer 4

In this case, char is just interpreted as a number and | and ^ are the bitwise operators OR and XOR, respectively.

Answer 5

It treats them as small integers. The | operator then does an OR and the ^ operator does an XOR (exclusive or), on the individual bits making up the integers. Neither operation is particularly useful for most character-based applications, but they can be used (for example) to add a parity bit to a char in comms programming.

Answer 6

| = Bitwise OR (inclusie OR)

^ = Bitwise XOR (exclusive OR)

Answer 7

They will be treated as the binary representation. This typically means unsigned 1 byte. Not true for all architectures!

(*a|*b) means either *a or *b or both contain anything else than '\0'

(*a^*b) means that the two characters are not identical.

Answer 8

The code just means:

while (*a != '\0' && *b != '\0')
   if (*a != *b)

The developer wanted to be clever using bitwise operators with the chars