How can I check if a string has special characters in C++ effectively?

user_407405 0
Viewed 76554

I am trying to find if there is better way to check if the string has special characters. In my case, anything other than alphanumeric and a '_' is considered a special character. Currently, I have a string that contains special characters such as std::string = "!@#$%^&". I then use the std::find_first_of () algorithm to check if any of the special characters are present in the string.

I was wondering how to do it based on whitelisting. I want to specify the lowercase/uppercase characters, numbers and an underscore in a string ( I don't want to list them. Is there any way I can specify the ascii range of some sort like [a-zA-Z0-9_]). How can I achieve this? Then I plan to use the std::find_first_not_of(). In this way I can mention what I actually want and check for the opposite.

whitelist c-strings c++ string
9 Answers

You can use something like this:

#include <ctype>

for(int i=0;i<s.length();i++){
    if( !std::isalpha(s[i]) && !std::isdigit(s[i]) && s[i]!='_')
          return false
}

The isalpha() function checks whether it is alphanumeric or not and isdigit() checks whether it is digit.

user_133146370
Related