c++ - 标记字符串

Question

我想要做的是按照这种格式输入一个日期 Wednesday 7:05 PM 然后将它分成标记以放入我拥有的结构中。我的主要问题是我正在使用的 stringstream 对象没有从输入缓冲区中删除已经输入的字符串，所以在我第二次检查数小时时它失败了，因为它输入了一个 char 类型的东西到一个无符号的。我该如何解决？另外，如果您对我清理代码有任何建议，我将不胜感激。

struct Time{
        //  always in [0, 6]:
        //  0 means Sunday, 1 means Monday, ... , 6 means Saturday
    unsigned day;
        //  false means at or after midnight, and before the following noon (AM)
        //  true means at or after noon, and before the following midnight (PM)
    bool pm;
    unsigned hour;      //  in [1, 12], e.g. 12 for 12 o’clock
    unsigned minute;    //  in [0, 59]
};  //  struct Time

const string dayar[]={"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

void input( Time & time ){
    string str, day, pm;
    unsigned hr, min;
    getline(cin,str);
    istringstream sin(str);
    cout<<str.length();
    for(unsigned i=0; i<str.length(); i++){
        if(str[i]==':')
            str[i]=' ';
    }
    if(!(sin>>day)){
        die("AHHHHH!!! WHERE'S THE INPUT?!?!?!");
    }else{
        for(unsigned i=0; i<7; i++){
            if(day==dayar[i]){
                time.day=i;
            }
        }
    }
    if(!(sin>>hr)){
        die("AHHHHH!!! WHERE'S THE INPUT?!?!?!");
    }else{
        if(hr<1 || hr>12){
            die("THAT NUMBER AIN'T A REAL HOUR!!");
        }else{
            time.hour=hr;
        }
    }
    if(!(sin>>min)){
        die("AHHHHH!!! WHERE'S THE INPUT?!?!?!");
    }else{
        if(min<0 || min>59){
            die("THAT NUMBER AIN'T A REAL HOUR!!");
        }else{
            time.minute=min;
        }
    }
    if(!(sin>>pm)){
        die("AHHHHH!!! WHERE'S THE INPUT?!?!?!");
    }else{
        if(pm!="PM" || pm!="AM"){
            die("THAT NUMBER AIN'T A REAL HOUR!!");
        }else{
            pm=="PM"?time.pm=true:time.pm=false;
        }
    }
}

bool die(const char *msg){
    cout<<msg;
    exit(EXIT_FAILURE);
}

Answer 1

当您将冒号更改为空格时，您可以正确更改字符串，但不会更改输入流缓冲的内容。

在声明输入流之前更改冒号。

此外，还有更好和更多的“C++-ish”方式来做到这一点，例如使用std::transform :

#include <algorithm>

// ...

std::transform(str.begin(), str.end(), str.begin(),
    [](const char c){ return (c == ':' ? ' ' : c); });