Question

我想要做的是检查用户提供的字符串是否有大写字母。带有枚举常量的代码的第一部分就是另一种方法，我使用分配给星期日= 7，星期一= 1，星期二= 2等字的数字来工作。我正在尝试让用户不提供数字，但实际的字（周日，周一，周二），但我希望他们用大写字母指定星期几。

我得到的问题：编译得很好，但是你输入的任何内容都会以某种方式重定向到执行路径，该执行路径始终返回“使用大写字母重新输入”。如果我输入fjdkalfda或sunday或Sunday或其他任何内容，就会发生这种情况。这是代码。对不起，如果它不是代码格式，Stack Overflow的第一次用户。

#include <iostream>
#include <string>
#include <cstring>
using namespace std;

int main(){  
    /*enum DaysOfWeek {
        Monday = 1,
        Tuesday,
        Wednesday,
        Thursday,
        Friday,
        Saturday,
        Sunday
    };*/  //I'm not using this, but I can get my code to work with this
          //enumerated constant by asking the user to input a number corresponding
          //to the day of the week and then using if-else statements to check, say, 
          // int Day;
          // cin >> Day
          // then use if statements to check if Day = a certain number, to give output

    cout << "Enter the day of week with a capital letter: ";
    string Day;
    getline(cin, Day);
    if (Day == ("monday") || ("tuesday"))
        cout << "Retype w/ a capital letter" << endl;
    else if (Day == ("wednesday") || ("thursday"))
        cout << "Retype w/ a capital letter" << endl;
    else if (Day == ("friday") || ("saturday"))
        cout << "Retype w/ a capital letter" << endl;
    else if (Day  == ("sunday"))
        cout << "Retype w/ a capital letter" << endl;
    else
    {
        if (Day == "Monday")
            cout << "Moon" << endl;
        else if (Day == "Tuesday")
            cout << "Mars" << endl;  //continue with the days etc...
    }
    return 0;
}

Answer 1

人们会发现有一个名为 toupper 的函数可以将小写字母转换为大写字母，并单独留下大写字母。也许你可以重复使用这个函数来帮助用更少的代码来解决你的问题。

我从你的代码中推断出你只想验证第一个字母是大写字母。这是对的吗？

Answer 2

ctype.h中有一个isupper函数，如果char为大写，则返回true：

#include <ctype.h>

...
isCapitalized = isupper(str[0]);
...

Answer 3

如果我们能以某种方式组织enum类型的输入选择，我假设你实际上并不关心国会大厦的字母。如果您有enum classes，那么取代C++11将是更好的选择。如果没有，那么为常规枚举更改此代码将非常容易

如果您使用的是gcc / g ++，则可能需要包含前缀-std=c++11

注意：您可能希望将另一个enum元素添加到enum class Days，例如null_day。或者甚至更好，确保用户输入正确的日期，直到他/她做，不要继续使用程序（提示：使用while时使用getline循环

#include <iostream>
#include <string>
#include <cstring>
#include <algorithm>

using std::string;
using std::transform;
using std::cout;
using std::cin;
using std::endl;

// only in C++ 11
enum class Day {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday};    

int main () {  

cout << "Enter the day of week: ";

// store day from user input, transform all to lower case so
// we don't bother with user input type (only error in spelling will be the problem now)
string get_day;
getline(cin, get_day);
transform(get_day.begin(), get_day.end(), get_day.begin(), tolower);

// define instance of enum class Day, and sort out what day user has input
// note that if you do not initialize myDay object, it will set to the first
// element in the enum class Day above (which is Monday). This will happen 
// if user input is not allowed to initialize it. See the << >> section below
Day myDay;
if (get_day == "monday")
    myDay = Day::Monday;
else if (get_day == "tuesday")
    myDay = Day::Tuesday;
else if (get_day == "wednesday")
    myDay = Day::Wednesday;
else if (get_day == "thursday")
    myDay = Day::Thursday;
else if (get_day == "friday")
    myDay = Day::Friday;    
else if (get_day == "saturday")
    myDay = Day::Saturday;
else if (get_day == "sunday")
    myDay = Day::Sunday;
else
    << ERROR CODE HERE >>
    << MAYBE A WHILE LOOP UNTIL USER INPUTS CORRECT DATA >>

// perform your calculations/operations/etc separate from above
if (myDay == Day::Monday)
    cout << "Moon" << endl;

else if (myDay == Day::Tuesday)
    cout << "Mars" << endl;  //continue with the days etc...

return 0;

}

收到一个字符串，检查大写字母

3 个答案: