Я очень новичок в этом мире C ++ и пытаюсь написать функцию проверки ввода для числового пароля. Это то, что я получил так далеко:

<code>#include <iostream>
#include <limits>
using namespace std;

void isNumeric(int &iN)
{
    while (1) {
        cin >> iN;

        if (cin.fail()) {
            cin.clear();
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
            cout << "Only 'numeric' value(s) are allowed: ";
            continue;
        }

        // alpha-numeric entry also not allowed 
        cin.ignore(numeric_limits<streamsize>::max(), '\n');
        if (cin.gcount() >  1) continue;

        // check against the -ve value
        if (iN <= 0 ) continue;

    break;
    }
}

int main()
{
    int x;

    cout << "Enter your number: ";
    isNumeric(x);
    cout << "You've entered: " << x << endl;

    return 0;
}
</code>

Он просто отлично работает для неправильных значений, но не прерывает цикл при правильной записи. Есть идеи, что мне здесь не хватает? Ура !!

ErroR from James Kanze's script:

<code>test.cpp: In function ‘bool parseNumber(const string&, int&)’:
test.cpp:11:20: error: no match for ‘operator>>’ in ‘text >> results’
test.cpp:11:20: note: candidates are:
/usr/include/c++/4.6/bits/basic_string.tcc:998:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::basic_string<_CharT, _Traits, _Alloc>&)
/usr/include/c++/4.6/bits/istream.tcc:957:5: note: template<class _CharT2, class _Traits2> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT2*)
/usr/include/c++/4.6/bits/istream.tcc:925:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT&)
/usr/include/c++/4.6/istream:709:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char&)
/usr/include/c++/4.6/istream:714:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char&)
/usr/include/c++/4.6/istream:756:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char*)
/usr/include/c++/4.6/istream:761:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*)
test.cpp:11:42: error: ‘const string’ has no member named ‘peek’
test.cpp:11:52: error: ‘EOF’ was not declared in this scope
</code>

Новый код:using getline() and validation as a string Thanks everyone (especially James Kanze) for helping me out. This thing is pretty much working here.

<code>void isNumeric( int &iN )
{
    string sN; 

    while (1) {
        getline(cin, sN);

        bool valNum = true;
        for ( unsigned iDx=0; iDx < sN.length(); iDx++ )
            if ( !isdigit(sN[iDx]) ) { 
                valNum = false;
                break;
            }   

        if ( !valNum ) { 
            cout << "Wrong entry; Try again: ";
            continue;
        }   

        stringstream sStream (sN );
        sStream >> iN; 

        if ( iN<=0 ) {
            cout << "Cannot be 0; Try again: "; 
            continue;
        }     
    break;   
    }   
}
</code>

Есть ли здесь место для дальнейшего улучшения? Ура !!