CIN是不是在等待输入

Question

这是程序：

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


using namespace std; 

int main(){ 


string strKingdom = ""; 
bool conquered_me;//see if was conquered, was going to use this on other program and true = game over. 
int gold; 
int food; 
int citizens; 
int soldiers; 



cout << endl <<"Name of kingdom: "; 
cin >> strKingdom; 
cout << endl << "were you conquered (true/false): "; 
cin >> conquered_me; 
cout << endl << "How many gold do you have?:"; 
cin>>gold; 
cout << endl << "How many food do you have?:"; 
cin >> food; 
cout << endl << "How many citizens do you have?:"; 
cin >> citizens; 
cout << endl << "How many soldiers do you have?:"; 
cin >> soldiers; 


return 0; 
} 

的问题是，当我编译它的编程'只让我插入的第2个变量，然后它显示的剩余的问题（编译后）：

王国的名字：史蒂夫

是你征服（真/假）：假

多少黄金，你有？： 多少FOO d你有吗？： 你有几个公民？： 你有几个士兵？：

Answer 1

您需要使用std :: getline和std :: string来读取各种值。 （然后你可以使用像atoi这样的函数来解析它们。）以下是使用std :: getline函数的代码示例。

#include <iostream> 
#include <string> 
#include <cstdlib> 

int main(){ 


std::string strKingdom = ""; 
bool conquered_me;//see if was conquered, was going to use this on other program and true = game over. 
int gold; 
int food; 
int citizens; 
int soldiers; 

std::string tString = ""; // Used to read and subsequently parse the string. 


std::cout << std::endl <<"Name of kingdom: "; 
std::getline(std::cin,strKingdom); 

std::cout << std::endl << "were you conquered (true/false): "; 
std::getline(std::cin,tString); 
conquered_me = (tString == "true"); 

std::cout << std::endl << "How many gold do you have?:"; 
std::getline(std::cin,tString); 
gold = std::atoi(tString.c_str()); 

std::cout << std::endl << "How many food do you have?:"; 
std::getline(std::cin,tString); 
food = std::atoi(tString.c_str()); 

std::cout << std::endl << "How many citizens do you have?:"; 
std::getline(std::cin,tString); 
citizens = std::atoi(tString.c_str()); 

std::cout << std::endl << "How many soldiers do you have?:"; 
std::getline(std::cin,tString); 
soldiers = std::atoi(tString.c_str()); 


return 0; 
} 

Answer 2

输入字符串“true”到bool变量不起作用。您应该输入1或0。你的“真”不能被“消耗”，所以它留在缓冲区中。接下来，您正尝试读取int的值，因此“true”也不匹配。等...直到节目结束。

这就是我该怎么做：

#include <string> 
#include <iostream> 

#include <errno.h> 
#include <stdlib.h> 

using namespace std; 

void askForString(string aPrompt, string &aValue) { 
    cout << aPrompt << " "; 
    cin >> aValue; 
} 

void askForBool(string aPrompt, bool &aValue) { 
    string tString; 
    while (1) { 
     cout << aPrompt << " "; 
     cin >> tString; 
     if (tString == "true") { 
      aValue = true; 
      break; 
     } else if (tString == "false") { 
      aValue = false; 
      break; 
     } else { 
      cout << "Repeat, please?" << endl; 
     } 
    } 
} 

void askForInt(string aPrompt, int &aValue) { 
    string tString; 
    char *endptr; 
    while (1) { 
     cout << aPrompt << " "; 
     cin >> tString; 
     errno = 0; 
     aValue = strtol(tString.c_str(), &endptr, 10); 
     if (errno || tString.c_str() == endptr || (endptr != NULL && *endptr != 0)) { 
      cout << "Repeat, please?" << endl; 
     } else { 
      break; 
     } 
    } 
} 

int main(void) { 
    string strKingdom; 
    bool conquered_me; 
    int gold; 
    int food; 
    int citizens; 
    int soldiers; 

    askForString("Name of kingdom:", strKingdom); 

    askForBool("were you conquered (true/false):", conquered_me); 

    askForInt("How many gold do you have?:", gold); 

    askForInt("How many food do you have?:", food); 

    askForInt("How many citizens do you have?:", citizens); 

    askForInt("How many soldiers do you have?:", soldiers); 

    cout << "Kingdom: " << strKingdom << endl; 
    cout << "Conquered: " << (conquered_me ? "true" : "false") << endl; 
    cout << "Gold: " << gold << endl; 
    cout << "Food: " << food << endl; 
    cout << "Citizens: " << citizens << endl; 
    cout << "Soldiers: " << soldiers << endl; 

    return 0; 
} 

Answer 3

把他们都转换为字符串，并根据需要转换。

Answer 4

您的阅读命令都没有检查错误。所有的这些都应该被写成这样：

while (!(std::cin >> strKingdom)) { 
    std::cerr << 'Bad input' << std::endl; 
    std::cin.clear(); // clear the error 
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // ignore the rest of the line 
    // output the same prompt again? 
} 

为了使这个简单，你可能想要写一个辅助函数：

template<typename T> void get_input(const char *prompt, T &result) { 
    std::cout << prompt << std::endl; 
    while (!(std::cin >> result)) { 
     std::cerr << 'Bad input' << std::endl; 
     std::cin.clear(); 
     std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); 
     std::cout << prompt << std::endl; } } 

然后，您可以专注，对于布尔类型的阅读真/假正确...

Answer 5

这条线：

cin >> conquered_me; 

应该是这样的：

cin >> boolalpha >> conquered_me; 

否则，输入需要“0”或“1”。

使用boolalpha您的输入可以是“真”或“假。

Answer 6

出于某种原因（可能与旧代码的兼容性）iostreams的默认我在转换true到1和false到0/O。

这只是默认设置 - 有一个名为boolalpha的操纵器，它会将流设置为使用true和false（或本地等效项）。

所以，这样的代码：

std::cout << 1 == 0;    // produces `0` 
std::cout << boolalpha << 1 == 0; // produces `false` 

这也适用于输入，这样你就可以改变你的代码是这样的：

cin >> boolalpha >> conquered_me; 

...并预期它应该工作（在：它应该接受false或true的输入，并从中产生值false和true，如果它不是标准库中的错误）。