游戏的 C++ 输入验证

Question

我正在努力让输入验证适用于我的游戏。

#include <iostream>
#include <ctime>
using namespace std;

int main()
{

    int iGumballs;
    int iUserguess;
    int iGuesses = 0;

    while (true)
    {
        system("CLS");
        cin.clear();
        iGuesses = 0;

    srand(static_cast<unsigned int>(time(0)));
    iGumballs = rand()%1000+1;
    cout << "How many gumballs are in the bumball jar? You guess! 1-1000" << endl;

    do
    {
        cout << "Enter your guess: ";


    cin >> iUserguess;


    if(iUserguess > iGumballs)
    {
        cout << "Too high!" << endl << endl;
    }

    if(iUserguess < iGumballs)
    {
        cout << "Too low!" << endl << endl;
    }
    iGuesses ++;
    }
    while(iUserguess > iGumballs || iUserguess < iGumballs);
    cout << "You guessed the right amout of gumballs" << endl << endl;
    cout << "You took " << iGuesses << " guesses" << endl << endl;
    system ("pause");
    }
    return 0;
}

我基本上是想让程序显示

Your Guess: Sorry, incorrect input - try again

当用户输入小于 1 且大于 1000 的数字时，以及某种确保输入数字而不是字母或符号的验证。我尝试了 cin.fail()，但无法正常工作。

谢谢， 约翰

Answer 1

你需要一些测试来判断是不是一个数字，试试这个:

#include <iostream>
#include <string>
#include <ctime>
#include <boost/lexical_cast.hpp> //dependency that can be optional
using namespace std;

bool is_number(const std::string& s)
{
    std::string::const_iterator it = s.begin();
    while (it != s.end() && std::isdigit(*it)) ++it;
    return !s.empty() && it == s.end();
}

int main()
{

    int iGumballs;
    std::string iUserguessStr;
    int iUserguess;
    int iGuesses = 0;

    while (true)
    {
        system("CLS");
        cin.clear();
        iGuesses = 0;

    srand(static_cast<unsigned int>(time(0)));
    iGumballs = rand()%1000+1;
    cout << "How many gumballs are in the bumball jar? You guess! 1-1000" << endl;

    do
    {
        cout << "Enter your guess: ";


    cin >> iUserguessStr;
    if(is_number(iUserguessStr))
        iUserguess = boost::lexical_cast<int>(iUserguessStr); //you can make your own or maybe use lexical cast to transform a string into integer
    else
        continue; //put some fancy message here warning the user


    if(iUserguess > iGumballs)
    {
        cout << "Too high!" << endl << endl;
    }

    if(iUserguess < iGumballs)
    {
        cout << "Too low!" << endl << endl;
    }
    iGuesses ++;
    }
    while(iUserguess > iGumballs || iUserguess < iGumballs);
    cout << "You guessed the right amout of gumballs" << endl << endl;
    cout << "You took " << iGuesses << " guesses" << endl << endl;
    system ("pause");
    }
    return 0;
}

我的回答是基于一个相关问题:How to determine if a string is a number with C++?