Cast int as byte array in C++

Question

I am trying to use implement the LSB lookup method suggested by Andrew Grant in an answer to this question: Position of least significant bit that is set

However, it's resulting in a segmentation fault. Here is a small program demonstrating the problem:

#include <iostream>

typedef unsigned char Byte;

int main()  
{  
    int value = 300;  
    Byte* byteArray = (Byte*)value;  
    if (byteArray[0] > 0)  
    {  
        std::cout<< "This line is never reached. Trying to access the array index results in a seg-fault." << std::endl;  
    }  
    return 0;  
}  

What am I doing wrong?
I've read that it's not good practice to use 'C-Style' casts in C++. Should I use reinterpret_cast<Byte*>(value) instead? This still results in a segmentation fault, though.

Solution 1

Use this:

(Byte*) &value;

You don't want a pointer to address 300, you want a pointer to where 300 is stored. So, you use the address-of operator & to get the address of value.

Solution 2

While Erik answered your overall question, as a followup I would say emphatically -- yes, reinterpret_cast should be used rather than a C-style cast.

Byte* byteArray = reinterpret_cast<Byte*>(&value);

Solution 3

The line should be: Byte* byteArray = (Byte*)&value;

You should not have to put the (void *) in front of it.

-Chert