Convert array of uint8_t (uint8_t*) to string in C++ [3 methods]

In this article, we have presented different ways to convert an array of uint8_t (uint8_t*) to string in C++.

Table of contents:

1. Introduction to array of uint8_t (uint8_t*) and string
2. Approach 1: Explicit Casting
3. Approach 2: reinterpret_cast
4. Approach 3: ostringstream

Introduction to array of uint8_t (uint8_t*) and string

uint8_t is a typedef for char so the compiler treats it as an ASCII character. The size of uint8_t is 8 bits (1 byte) and the size of char is same (1 byte).

String is a special datatype in C++ and is equivalent to an array of characters that is char*.

In this case, we are converting array of uint8_t that is uint8_t*. So, uint8_t* is equivalent to char* or string.

Approach 1: Explicit Casting

As uint8 and char are same, so an array of uint8_t can be converted to an array of char just by casting. Once we get an array of char, assigning it to a string completes the conversion.

uint8_t* input = {12, 1, 65, 90};
char* input2 = (char *) input;
string input3 = input2;

Following is the complete C++ code using explicit casting:

#include <stdlib.h>

int main() {
  uint8_t* input = {12, 1, 65, 90};
  char* input2 = (char *) input;
  string input3 = input2;
  return 0;
}

Approach 2: reinterpret_cast

As alternative to explicit casting will be to use reinterpret_cast.

uint8_t* input = {12, 1, 65, 90};
std::string str = reinterpret_cast<char *>(input);

Following is the complete C++ code using reinterpret_cast:

#include <stdlib.h>

int main() {
  uint8_t* input = {12, 1, 65, 90};
  std::string str = reinterpret_cast<char *>(input);
  return 0;
}

Approach 3: ostringstream

ostringstream is a builder where each element from the uint8_t array is appended one by one. Following it, calling the str() method of ostringstream returns the string.

uint8_t* input = {12, 1, 65, 90};
std::ostringstream convert;
for (int i = 0; i < 4; i++) {
    convert << (int)input[i];
}
std::string key_string = convert.str();

Following is the complete C++ code using ostringstream:

#include <stdlib.h>

int main() {
  uint8_t* input = {12, 1, 65, 90};
  std::ostringstream convert;
  for (int i = 0; i < 4; i++) {
      convert << (int)input[i];
  }
  std::string key_string = convert.str();
  return 0;
}

With this article at OpenGenus, you must have the complete idea of how to convert array of uint8_t (uint8_t*) to string in C++.