C++ convert int and string to char*

Question

This is a little hard I can't figure it out.

I have an int and a string that I need to store it as a char*, the int must be in hex

i.e.

int a = 31;
string str = "a number";

I need to put both separate by a tab into a char*.

Output should be like this:

1F      a number

Answer 1

With appropriate includes:

#include <sstream>
#include <ostream>
#include <iomanip>

Something like this:

std::ostringstream oss;
oss << std::hex << a << '\t' << str << '\n';

Copy the result from:

oss.str().c_str()

Note that the result of c_str is a temporary(!) const char* so if your function takes char * you will need to allocate a mutable copy somewhere. (Perhaps copy it to a std::vector<char>.)

Answer 2

Try this:

int myInt = 31;
const char* myString = "a number";
std::string stdString = "a number";

char myString[100];

// from const char*
sprintf(myString, "%x\t%s", myInt, myString);

// from std::string   :)
sprintf(myString, "%x\t%s", myInt, stdString.c_str());