#include
#include
#include
#include
#include
using namespace std;
bool isNumber(const string& str)
{
string::const_iterator it = find_if(str.begin(), str.end(), not1(ptr_fun(::isdigit)));
return (it == str.end());
}
int main(int argc, char** argv)
{
cout << isNumber("12345") << endl;
cout << isNumber("hello") << endl;
cout << isNumber("1234a") << endl;
return (0);
}