CODEWITHSUNDEEP
c++string
user3596335
user3596335

Reputation:

String includes just valid chars?

I'd like to valid a string to check if the string just includes valid characters or not using C++.

Valid characters should be given to the function like as charset of valid characters: "abc123".

A string that just includes the characters given in the charset above should return true while a string that also includes other characters then given should return false. Obviously a easy task :)

--> using charset abc123:

string myString_1 = "bbbac1" // should get true 
string myString_2 = "bbbac132aacc" // should get true 

string myString_3 = "xxxxxx" // should get false
string myString_4 = "bbbac12533cc" // should get false

How can I implement a call like this in C++?

Note: I though about using something like the code below but I'm pretty sure theres a way better solution.

string charset = "abc123";
string myString = "bbbac1";

for (int i=0; i<charset.length(); i++) {
  std::replace( myString.begin(), myString.end(), charset[i], '');
}
bool isValid = (myString.length() == 0);

Upvotes: 0

Views: 756

Answers (2)

bolov
bolov

Reputation: 75924

AS igor-tandetnik pointed in comments this is a job for std::find_first_not_of:

auto validate(const std::string& str, const std::string& charset) -> bool
{
    return str.find_first_not_of(charset) == std::string::npos;
}

Upvotes: 1

L. Kue
L. Kue

Reputation: 473

You can write your own check function:

bool checkstring(std::string &checkstring, std::string &legalchars) {
    for (char c : checkstring) {
        // resetting the bool
        bool isLegal = false;
        for (char d : legalchars) {
            // comparing the chars
            if (c == d) { isLegal = true; }
        }
        // if a non-legal char was found, return false
        if (!isLegal) { return false; }
    }
    // if no non-legal character was found, return true
    return true;
}

Although there might be a better alternative using the standard libraries, especially if you need to compare very long strings with a large set of legal characters.

Upvotes: 0

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