初學C++輸入法beiviviour

Question

這個程序是我學習C++的一個非常簡單的代碼。問題是在某些時候它不接受來自cin的輸入並且表現奇怪。 該程序的代碼和輸出如下。

爲什麼程序在「請輸入你的名字」時不考慮cin？

# include "cmath" 
# include <iostream> 
using namespace std; 

int main() 
{ 
    string FirstName, MiddleName, LastName; 
    string WelcomeMessage = "Welcome to Visual C++"; 
    int Number_of_Steps = 5; 
    int LoopStart = 1, LoopEnd = 5; 
    int AgeYears, AgeMonths; 
    double Pi = 3.14; 
    float k = 5.366; 
    double Age; 
    char* Symbol = "k"; 
    bool TestResult = true; 

    MiddleName = "Milton"; 

    cout << "Input Your First Name and Last Name" << endl; 
    cin >> FirstName >> LastName; 
    cout << "Input your Age in Years" << endl; 
    cin >> AgeYears; 
    cout << "Imput your Age in Months " << endl; 
    cin >> AgeMonths; 
    Age = AgeYears + AgeMonths/12; 
    cout << endl << "Your Name is " << FirstName << ' ' << LastName << endl; 
    cout << "Your Age is " << Age << endl; 
    cout << "The Character is " << Symbol << endl; 

    // Testing operators 
    cout << "Please Enter a floating point number \n"; 
    int n; 
    cin >> n; 
    cout << "n==" << n 
     << "\n n+1==" << n + 1 
     << "\n n three times==" << 3 * n 
     << "\n n twice ==" << n + n 
     << "\n nsquared ==" << n*n 
     << "\n half of n ==" << n/2 
     << "\n square root of n ==" << sqrt(n) 
     << "\n";  

    // Testing string addition 
    cout << "Eneter your first name please" << endl; 
    string String1, String2, String3; 
    cin >> String1; 
    cout << "Enter your family name please" << endl; 
    cin >> String2; 
    String3 = String1 + " " + String2; 
    cout << "Welcome" << " " << String3 << endl; 

    // testing inequalities to strings 
    string FirstString, SecondString; 
    cout << "Input First String " 
     << endl; 
    cin >> FirstString; 
    cout << "Input Second String " 
     << endl; 
    cin >> SecondString; 
    if (FirstString == SecondString) 
     cout << "The two words are identical \n"; 
    if (FirstString >= SecondString) 
     cout << "First word is bigger than second word \n"; 
    if (FirstString <= SecondString) 
     cout << "Second word is bigger than first word \n"; 
} 

Answer 1

你從顯示.2作爲第一個名稱（String1）輸出的提示。詢問名字前的cin操作在緩衝區上有64.2，但由於您將該值讀入int n，它只讀取整數部分64並將.2保留在緩衝區上。將聲明n更改爲float n或者如果您確實需要一個整數進行一些輸入驗證，則當您到達名字請求時應該將緩衝區留空。