我很難調試很長的編譯時間和多用戶輸入要求

Question

我需要絕望的幫助，因爲我無法弄清楚爲什麼和我做錯了什麼。我試圖向用戶詢問關於長度轉換的多個問題。我遇到了一個問題，只有第一個問題被問到，而下一個問題沒有機會被問到。我試過兩個版本，但都是有缺陷的。

Sample output:

Sisestage pikkus meetrides: 
500 
Sisestage uue uhiku kood (alj, ver, kyn, toll, jalg, jard, lii): 
Sisestasite vale vaartuse:500 void vale uhiku: 

我的代碼：

#include <iostream> 
#include <iomanip> 
#include <string> 
#include <string.h> 

using namespace std; 

int main() 
{ 

    float P;    /* Pikkus meetrites */ /*Length P in metres*/ 
    string U;    /* M66du:hik*/ /* Unit of measure*/ 

    float ALJ; 
    float VER; 
    float KYN; 
    float TOLL; 
    float JALG; 
    float JARD; 
    float LII; 

    do 
    { 
     cout<<"Sisestage pikkus meetrides: \n"; /*Ku:sin kasutajalt pikkust P*/ /* Asking  user for the length P in metres*/ 
     cin>>P; 
     if (P > 0) 
      cout<<"Sisestage uue uhiku kood (alj, ver, kyn, toll, jalg, jard, lii): \n"; /* Ku:sin   kasutajalt u:hiku koodi U*/ /* Asking user for the length U in metres*/ 
     getline(cin, U); 
    } while (P > 0);  
    cout << "Sisestasite vale vaartuse:"<<P<< endl; /*Veateade*/ 
    ALJ = P/5572; 
    VER = P/1066.781; 
    KYN = P/0.53; 
    TOLL = P/0.0254; 
    JALG = P/0.3048; 
    JARD = P/0.9144; 
    LII = P/500; 


    if(U == "alj") 
    { 
     cout<< setprecision(2)<<fixed<< P <<"m = "<< ALJ << U <<"." ; 
    } 
    else if(U == "ver") 
    { 
     cout<< setprecision(2) << fixed << P <<" m ="<< VER << U <<"."; 
    } 
    else if(U == "kyn") 
    { 
     cout<< setprecision(2) << fixed << P <<" m ="<< KYN << U <<"."; 
    } 
    else if(U == "toll") 
    { 
     cout<< setprecision(2) << fixed << P <<" m ="<< TOLL << U <<"."; 
    } 
    else if(U == "jalg") 
    { 
     cout<< setprecision(2) << fixed << P<<" m ="<< JALG << U <<"."; 
    } 
    else if(U == "jard") 
    { 
     cout<< setprecision(2) << fixed << P <<" m ="<< JARD << U <<"."; 
    } 
    else if(U == "lii") 
    { 
     cout<< setprecision(2) << fixed << P <<" m ="<< LII << U <<"."; 
    } 


    getchar(); 
    getchar(); 

} 

Answer 1

這kind'a很難說這是怎麼回事這個缺口，但你的意思是包括在該函數getline如果（）塊？也許你錯過了{}

if (P > 0) 
cout<<"Sisestage uue uhiku kood (alj, ver, kyn, toll, jalg, jard, lii): \n"; /* Ku:sin   kasutajalt u:hiku koodi U*/ /* Asking user for the length U in metres*/ 
getline(cin, U); 

Answer 2

1.You不要有任何開放{和驗證關閉行}：

if (P > 0) 
cout<<"Sisestage uue uhiku kood (alj, ver, kyn, toll, jalg, jard, lii): \n"; /* Ku:sin   kasutajalt u:hiku koodi U*/ /* Asking user for the length U in metres*/ 
getline(cin, U); 

2.Fix您的縮進，因爲這使得這樣的錯誤更容易點。

Answer 3

難以混合operator<<與std::getline。前者在輸入流中留下行尾字符，這會混淆後者。

在致電operator<<之後，您必須消耗該行的其餘部分。這裏有兩種方法：

 // throw away rest of line 
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); 

或

std::string temp; 
std::getline(cin, temp); // throw away rest of line 

試試這個：

do 
{ 
    cout<<"Sisestage pikkus meetrides: \n"; /*Ku:sin kasutajalt pikkust P*/ /* Asking  user for the length P in metres*/ 
    cin>>P; 
    std::getline(cin, U); // throw away rest of line 
    if (P > 0) 
     cout<<"Sisestage uue uhiku kood (alj, ver, kyn, toll, jalg, jard, lii): \n"; /* Ku:sin   kasutajalt u:hiku koodi U*/ /* Asking user for the length U in metres*/ 
    getline(cin, U); // Start on fresh line 
} while (P > 0);  

正如其他人所指出的，你可能有if(P>0)代碼中的邏輯缺陷，但這是無關你的問題。