(C++) std::stoi

std::stoi is a C++11 STL function to convert a std::string to int.

Example: input can be converted to integer

#include <cassert>
#include <string>

int main()
{
  assert(std::stoi("123") == 123);
}

Example: input is no integer

If the input cannot be converted to integer, a std::invalid_argument is thrown.

#include <cassert>
#include <stdexcept>
#include <string>

int main()
{
  try
  {
    std::stoi("this is no int");
    assert(!"Should not get here");
  }
  catch (const std::invalid_argument&)
  {
    assert("OK");
  }
}

Example: input is a too big integer

If the input is a too big integer, a std::out_of_range is thrown.

#include <cassert>
#include <stdexcept>
#include <string>

int main()
{
  try
  {
    std::stoi("12345678901234567890123456789012345678901234567890");
    assert(!"Should not get here");
  }
  catch (const std::out_of_range&)
  {
    assert("OK");
  }
}

Example: handle both exceptions

#include <cassert>
#include <stdexcept>
#include <string>

int main()
{
  try
  {
    std::stoi("[your string here]");
    assert(!"Should not get here");
  }
  catch (const std::invalid_argument&)
  {
    assert("OK");
  }
  catch (const std::out_of_range&)
  {
    assert("OK");
  }
}

As an alternative, the base of both exceptions (called std::exception) can be used:

#include <cassert>
#include <stdexcept>
#include <string>

int main()
{
  try
  {
    std::stoi("[your string here]");
    assert(!"Should not get here");
  }
  catch (const std::exception&)
  {
    assert("OK");
  }
}

External links

• cppreference.com's page about std::stoi