Bitwise Operations in C

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1

Hey guys I am looking to generate a random 4 bit number in C and then shift the bits so I can access each bit. Could I see an example of how to do that?

2

This is simple stuff. Use random() from a standard library, in a cycle read modulo of 2, this will tell you what the rightmost bit is, then shift right by one, repeat until out of bits to read.

3

Since memory is byte-addressed you can't address something smaller than a byte. So you don't have a 4-bit pre-made data type (also called a nibble). But you can easily achieve this by using a struct or union and bit fields:

struct A {
    unsigned nibble1 : 4;
    unsigned nibble2 : 4;
};

In order to access the single bits of the binary rapresentation of let's say an int we use a bit mask and the logical &. For example this prints the binary rapresentation of an int:

/* Bit print an int expression. */ 

#include <limits.h> 

void bit_print(int a) 
{ 
    int i;
    int n = sizeof(int) * CHAR_BIT;
    int mask = 1 << (n-1);
    
    for (i = 1; i <= n; i++) {
        putchar(((a & mask) == 0) ? '0' : '1');
        a <<= 1;

        if (i % CHAR_BIT == 0 && i < n)
            putchar(' ');
    }
}