Easiest way to convert int to string in C++

Question

What is the easiest way to convert from int to equivalent string in C++. I am aware of two methods. Is there any easier way?

(1)

Answer 1

I usually use the following method:

#include <sstream>

template <typename T>
  std::string NumberToString ( T Number )
  {
     std::ostringstream ss;
     ss << Number;
     return ss.str();
  }

It is described in details here.

Answer 2

I use:

int myint = 0;
long double myLD = 0.0;

string myint_str = static_cast<ostringstream*>(&(ostringstream() << myint))->str();
string myLD_str = static_cast<ostringstream*>(&(ostringstream() << myLD))->str();

It works on my Windows and Linux g++ compilers.

Answer 3

C++17 provides std::to_chars as a higher-performance locale-independent alternative.

Answer 4

Here's another easy way to do

char str[100];
sprintf(str, "%d", 101);
string s = str;

sprintf is a well-known one to insert any data into a string of the required format.

You can convert a char * array to a string as shown in the third line.

Answer 5

You can use std::to_string available in C++11 as suggested by Matthieu M.:

std::to_string(42);

Or, if performance is critical (for example, if you do lots of conversions), you can use fmt::format_int from the {fmt} library to convert an integer to std::string:

fmt::format_int(42).str();

Or a C string:

fmt::format_int f(42);
f.c_str();

The latter doesn't do any dynamic memory allocations and is more than 10 times faster than std::to_string on Boost Karma benchmarks. See Fast integer to string conversion in C++ for more details.

Note that both are thread-safe.

Unlike std::to_string, fmt::format_int doesn't require C++11 and works with any C++ compiler.

Disclaimer: I'm the author of the {fmt} library.

Answer 6

First include:

#include <string>
#include <sstream>

Second add the method:

template <typename T>
string NumberToString(T pNumber)
{
 ostringstream oOStrStream;
 oOStrStream << pNumber;
 return oOStrStream.str();
}

Use the method like this:

NumberToString(69);

or

int x = 69;
string vStr = NumberToString(x) + " Hello word!."