用户输入的C ++字符串验证

Question

All I want to do, is prompt a user for a yes or no answer, and validate this to ensure they haven't typed something stupid.

I thought this would be a relatively straight forward task, however after many failed attempts at it myself, and looking around online, it seems everyone has a different opinion on the best way to do it.

Pseudocode

1. Ask question

2. prompt user

3. check if input = yes or input = no

4. if yes, do scenario a

5. in no, do scenario b

6. if invalid, return to point 2

Code

main.cpp

std::cout << "Do you have a user name? ("yes", "no"): ";
std::cin >> choice;
user.validation(choice);

if (choice == "yes")
{
// some code
}

if (choice == "no")
{
// some code
}

User.cpp

void User::validation(std::string choice)
{
    while (choice != "yes" && choice != "no")
    {       
        std::cout << "Error: Please enter 'yes' or 'no': ";
        std::cin >> choice;
        if (choice == "yes" && choice == "no")
        {
            break;
        }

    }
}

This works, up until they eventually type yes or no, when it jumps past if yes, and if no, straight onto the next part of the program

And I want to be able to call user.validation multiple times throughout the program to validate other yes/no questions

Answer 1

Try changing this

if (choice == "yes" && choice == "no")

For this

if (choice == "yes" || choice == "no")

Choice cannot be "yes" and "no" at the same time.

Answer 2

您没有从validation()返回正确的choice ：

void User::validation(std::string &choice) // <-- insert a & here

Answer 3

C/C++ doesn't work like this for strings as the == operator isn't doing what you think it's doing for std::string objects and char* arrays. Use the std::string compare() method instead. Reference: http://www.cplusplus.com/reference/string/string/compare/