(C++) IsInt

IsInt is a checking code snippet to check if a std::string can be converted to an integer.

CanCast and CanLexicalCast are more general versions of IsInt.

Technical facts

Operating system(s) or programming environment(s)

Lubuntu 15.04 (vivid)

IDE(s):

Qt Creator 3.1.1

Project type:

Console application

C++ standard:

C++98

Compiler(s):

G++ 4.9.2

Libraries used:

STL: GNU ISO C++ Library, version 4.9.2

Qt project file: ./CppIsInt/CppIsInt.pro


include(../../ConsoleApplication.pri)

include(../../Libraries/Boost.pri)



SOURCES += main.cpp

./CppIsInt/main.cpp


#include <sstream>



///IsInt determines if std::string can be converted to integer.

///From http://www.richelbilderbeek.nl/CppIsInt.htm

bool IsIntStl(const std::string& s)

{

  std::istringstream i(s);

  int temp{0};

  i >> temp;

  if (!i) return false;

  char c{'\0'}; //Should be at end, if not, the string contained more than just a number

  i >> c;

  if (i) return false;

  return true;

}



#include <boost/lexical_cast.hpp>



///IsInt determines if std::string can be converted to integer.

///From http://www.richelbilderbeek.nl/CppIsInt.htm

bool IsIntBoost(const std::string& s) noexcept

{

  try

  {

    boost::lexical_cast<int>(s);

    return true;

  }

  catch (boost::bad_lexical_cast&)

  {

    return false;

  }

}



#include <cassert>



int main()

{

  assert(IsIntStl("3"));

  assert(IsIntStl("0"));

  assert(IsIntStl("-23"));

  assert(!IsIntStl("a"));

  assert(!IsIntStl("2+fire"));



  assert(IsIntBoost("3"));

  assert(IsIntBoost("0"));

  assert(IsIntBoost("-23"));

  assert(!IsIntBoost("a"));

  assert(!IsIntBoost("2+fire"));

}

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