CODEWITHSUNDEEP
c++arraysstring
Talisman
Talisman

Reputation: 388

Checking a string matches any string in a string array?

I'm looking for a way to check a string that a user inputs when prompted (let's take it to be a string variable "userinput") from an array of 10 other strings. So far I have:

    while (userinput.empty()) //Check for empty input
{
    cout << "Please enter your identity.\n"; //Identify user
    getline(cin, userinput);

    do //Check to see if user is the same as the string variable "user"
    {
    cout << "This user is either non existent or has access privileges revoked.\n"; //Wrong username!
    cout << "Please re-enter the username.\n";
    getline(cin, userinput);
    }
    while (user != userinput);
}

It can be seen though, that this only works for a single string variable "user". How would I change this for a string array?

The array itself is the following:

string arr[10] = {"Test1", "Test2", "Test3", "Test4", "Test5", "Test6", "Test7", "Test8", "Test9", "Test10"};

Please note: I'm not intending to use passwords, only usernames.

Upvotes: 0

Views: 365

Answers (3)

Scis
Scis

Reputation: 2984

You can use the built-in count function like so:

do{
    getline(cin, userinput);
}
while(!std::count(arr, arr+10, userinput));

On ideone as well.

This is how your loop should look:

cout << "Please enter your identity.\n"; //Identify user
getline(cin, userinput);
while (!std::count(arr, arr+10, userinput)) //Check to see if user is the same as the string variable "user"
{
    cout << "This user is either non existent or has access privileges revoked.\n"; //Wrong username!
    cout << "Please re-enter the username.\n";
    getline(cin, userinput);
}

You can see it here.

Upvotes: 3

Alex
Alex

Reputation: 942

If you have a big number of strings to compare, then it will be much more efficiently to use a hash map (std::unordered_set) instead of an array. Search in a hash table is much faster then in an array.

unordered_set<string> valid_inputs {"Test1", "Test2", "Test3", "Test4", "Test5", "Test6"};

Then you can check an user input in such a way:

if (valid_inputs.find(user_input) == valid_inputs.end())
  cout << "error";
else
  cout << "success";

Upvotes: 1

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

Put the check in a separate function

 bool isValidUserName(const string& input) {
      for(int i = 0; i < 10; ++i) {
          if(input == arr[i]) {
              return true;
          }
      }
      return false;
 }

and use it as condition in the while

 while (!isValidUserName(userinput));

Upvotes: 2

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