CODEWITHSUNDEEP
c++comparisonbytebit
Walklikeapenguin
Walklikeapenguin

Reputation: 137

Directly compare Two 8 Bit (1 Byte) values in C++

I'm wondering, is there a way to compare 8 bit/1 byte values similarly to the way that we could compare an int?

For example:

// Start with these as false
bool int_comp = false;
bool byte_comp = false;

// Set the ints
int a_int = 128;
int b_int = 128;

// Set the bytes
char a_byte = 0xC0; // 11000000
char b_byte = 0xC0; // 11000000

// This comparison works
if (a_int == b_int)
   int_comp = true;

// This comparison does not work, however
if (a_byte == b_byte)
   byte_comp = true;

In this case the byte comparison does not work.. Is there a way to compare bytes in a way similar to how we compare integers?

Edit: As it turns out this does work- thank you for the replies. I was doing something extra in my code that I did not capture here that was causing the issues. Essentially I was using a static_cast and thought that it would work but it did not.

Here is what I was doing:

// Start with these as false
bool int_comp = false;
bool byte_comp = false;

// Set the ints
int a_int = 128;
int b_int = 128;

// Set the bytes
int8_t a_byte = 0xC0; // 11000000
char b_byte = 0xC0; // 11000000

// This comparison works
if (a_int == b_int)
   int_comp = true;

// This comparison does not work, however
//
// Turns out that using static_cast here did not do what I thought it would do,
// even though printing out the bits using std::bitset showed that the bits
// of the casted value were the same.
//
if (a_byte == static_cast<int8_t>(b_byte))
   byte_comp = true;

Upvotes: 0

Views: 2020

Answers (1)

eerorika
eerorika

Reputation: 238351

I'm wondering, is there a way to compare 8 bit values similarly to the way that we could compare an int?

Yes, there is. Example:

std::uint8_t a_octet = 0xC0; // 11000000
std::uint8_t b_octet = 0xC0; // 11000000
if (a_octet == b_octet)

... is there a way to compare 1 byte values ...

Yes, there is. Example:

unsigned char a_byte = 0xC0; // 11000000
unsigned char b_byte = 0xC0; // 11000000
if (a_byte == b_byte)

char a_byte = 0xC0; // 11000000

This doesn't work like you would expect on systems where the size of byte is 8 bits and char is a signed type because in such case 0xC0 is outside of representable values. The largest representable value would be 0x7f.

Otherwise your example works.

Upvotes: 3

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