OR operator in C not working

Question

I don't understand why the final printf in the code below is not printing 255.

char c;
c = c & 0;
printf("The value of c is %d", (int)c);
int j = 255;
c = (c | j);
printf("The value of c is %d", (int)c);

Answer 1

In most implementations the char type is signed, so it ranges from -128 to 127.

This means, 11111111 (which is 255 written in binary) is equal to -1. (As it's represented as a value stored in two's complement)

To get what you expect, you need to declare c as a unsigned char, like so:

unsigned char c = 0;
int j = 255;
c = (c | j);
printf("The value of c is %d", (int)c);