CODEWITHSUNDEEP
c++
Dean
Dean

Reputation: 517

Reading string from a byte[]

I have a byte array such as 0x21, 0x0D, 0x01, 0x03, 0x31, 0x32, 0x33 which containts the ascii string "123" with a length of 3. (string starts at 0x03, 0x31, 0x32, 0x33) I'm learning, So would somebody be able to show me how to get the output "123" from it and put it inside a char*? Many thanks

                BYTE Data[] = { 0x0D, 0x01, 0x03, 0x31, 0x32, 0x33 };
                int Length = Data[2];

                //Extract string "123" from Data and store as char* ?

Upvotes: 1

Views: 356

Answers (2)

perreal
perreal

Reputation: 98088

If you have char sized data in BYTE type:

#include <iostream>
typedef unsigned char BYTE;
BYTE Data[] = { 0x0D, 0x01, 0x03, 0x31, 0x32, 0x33 };

int main() {
  std::string str(reinterpret_cast<char*>(Data) + 3, 3); 
  std::cout << str << std::endl;
  const char * c = str.c_str();
  std::cout << c << std::endl;
  return 0;
}

Upvotes: 2

paulsm4
paulsm4

Reputation: 121809

Here is one example:

#include <windows.h> // typedef for BYTE
#include <stdio.h>
#include <ctype.h> // isnum(), isalpha(), isprint(), etc

BYTE bytes[] = {
  0x21, 0x0D, 0x01, 0x03, 0x31, 0x32, 0x33
};

#define NELMS(A) (sizeof(A) / sizeof(A[0]))

int 
main(int argc, char *argv[])
{
    char buff[80];
    for (int i=0, j=0; i < NELMS(bytes); i++) {
      if (isprint(bytes[i])) {
        buff[j++] = bytes[i];  
      }
    }
    buff[j] = '\0';
    printf ("buff=%s\n", buff);
    return 0;
}

EXAMPLE OUTPUT:

buff=!123

You'll notice that "0x21" is a printable character ("!"). Instead of "isprint()" (is a printable ASCII character), you can use "isalpha()", or "isalnum()" instead.

'Hope that helps!

Upvotes: 0

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