CODEWITHSUNDEEP
c++
spacer GIF
spacer GIF

Reputation: 705

How can I concatenate multiple chars into an int?

I'm using C++ to parse binary data from files. Each byte gets stored in a char array, at least when working from cplusplus.com's example. The issue here is that my data source uses 24-bit values, so bytes have to be combined.

Here is a very simple example. The desired output is AABB but the actual output is 165 due to it doing addition.

#include <iostream>
using namespace std;

int main() {
    unsigned char one = 0xAA;
    unsigned char two = 0xBB;
    unsigned int sum = one + two;
    cout << hex << sum << "\n";
    return 0;
}

Upvotes: 1

Views: 1489

Answers (2)

mattloulou
mattloulou

Reputation: 37

A very simple solution to this would be to use the 'left shift equals' <<= operator.

an example of what your code could do would be:

int main() {
    unsigned char one = 0xAA;
    unsigned char two = 0xBB;
    unsigned int sum = one;
    sum <<= 8; //This shifts the value of AA 8 bits to the left
    sum += two;

    cout << hex << sum << "\n";
    return 0;
}

Upvotes: 1

robthebloke
robthebloke

Reputation: 9672

uint32_t bytesTo24Bit(uint8_t hi, uint8_t mid, uint8_t low)
{
  return (uint32_t(hi) << 16) | (uint32_t(mid) << 8) | low;
}

Upvotes: 3

Related Questions