CODEWITHSUNDEEP
c++arraysbyte
Unicorn
Unicorn

Reputation: 2422

How to Convert unsigned char* to std::string in C++?

I have unsigned char*, want to convert it to std::string. Can you please tell me the safest way to do this?

Upvotes: 52

Views: 152313

Answers (6)

silentrandom
silentrandom

Reputation: 56

Here is the complete code

#include <bits/stdc++.h>

using namespace std;

typedef unsigned char BYTE;

int main() {
  //method 1;
  std::vector<BYTE> data = {'H','E','L','L','O','1','2','3'};
  //string constructor accepts only const char
  std::string s((const char*)&(data[0]), data.size());
  std::cout << s << std::endl;

  //method 2
  std::string s2(data.begin(),data.end());
  std::cout << s2 << std::endl;

  //method 3
  std::string s3(reinterpret_cast<char const*>(&data[0]), data.size()) ;
  std::cout << s3 << std::endl;
 
  return 0;
}

Upvotes: 2

Yacoby
Yacoby

Reputation: 55465

You just needed to cast the unsigned char into a char as the string class doesn't have a constructor that accepts unsigned char:

unsigned char* uc;
std::string s( reinterpret_cast< char const* >(uc) ) ;

However, you will need to use the length argument in the constructor if your byte array contains nulls, as if you don't, only part of the array will end up in the string (the array up to the first null)

size_t len;
unsigned char* uc;
std::string s( reinterpret_cast<char const*>(uc), len ) ;

Upvotes: 80

user2195463
user2195463

Reputation: 331

If has access to CryptoPP

Readable Hex String to unsigned char

std::string& hexed = "C23412341324AB";
uint8_t      buffer[64] = {0};
StringSource ssk(hexed, true,
            new HexDecoder(new ArraySink(buffer,sizeof(buffer))));

And back

std::string hexed;
uint8_t val[32]  = {0};
StringSource ss(val, sizeof(val), true,new HexEncoder(new StringSink(hexed));
// val == buffer

Upvotes: -1

spoulson
spoulson

Reputation: 21601

BYTE *str1 = "Hello World";
std::string str2((char *)str1);  /* construct on the stack */

Alternatively:

std::string *str3 = new std::string((char *)str1); /* construct on the heap */
cout << &str3;
delete str3;

Upvotes: 5

Charles Salvia
Charles Salvia

Reputation: 53339

BYTE* is probably a typedef for unsigned char*, but I can't say for sure. It would help if you tell us what BYTE is.

If BYTE* is unsigned char*, you can convert it to an std::string using the std::string range constructor, which will take two generic Iterators.

const BYTE* str1 = reinterpret_cast<const BYTE*> ("Hello World");
int len = strlen(reinterpret_cast<const char*>(str1));
std::string str2(str1, str1 + len);

That being said, are you sure this is a good idea? If BYTE is unsigned char it may contain non-ASCII characters, which can include NULLs. This will make strlen give an incorrect length.

Upvotes: 10

Satbir
Satbir

Reputation: 6506

BYTE is nothing but typedef unsigned char BYTE;

You can easily use any of below constructors

string ( const char * s, size_t n );
string ( const char * s );

Upvotes: 2

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