CODEWITHSUNDEEP
c++string
Nick Lewers
Nick Lewers

Reputation: 101

Trouble finding 'space' character in string

I have been struggling to get a simple function to work, the purpose is to pass in a character, the function then search's the ALPHABET string and then if the character is found, returns the index of the character within the string .

I have a basic constant containing the alphabet, including an apostrophe and space character:

const string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ.,’ ";

Now I have a function which takes a character as an argument: 

int charaPosition(string chara){

    transform(chara.begin(), chara.end(),chara.begin(), ::toupper);

    int charaIndex = ALPHABET.find(chara, 0);

    if (charaIndex != string::npos) {

        return charaIndex;

    }else{
        cout << "Not found" << endl;
   }
}

Function is initiated like so:

cout << charaPosition("s") << endl;

It all works fine up to a certain point, if I pass in A, the function returns 0, B return 1 etc. However if I pass in the space character, it returns 31 rather than 29, and if I pass in the apostrophe character, it just doesn't get found.

I would be very grateful for anyones help.

Upvotes: 2

Views: 211

Answers (1)

jweyrich
jweyrich

Reputation: 32240

Your problem is that ’ is not ASCII, it's Unicode. It occupies more than 1 byte in your string.

  1. It all works fine up to a certain point, if I pass in A, the function returns 0, B return 1 etc: Right, up to that point, it's all ASCII, so you have 1 byte per character, therefore all resulting indices make sense;

  2. However if I pass in the space character, it returns 31 rather than 29: The problem is that ’ occupies exactly 3 bytes (226 128 153) rather than 1 byte, because it's Unicode. You should use std::wstring and wchar_t to make this work properly, or replace that character by ' (ASCII 39);

  3. and if I pass in the apostrophe character, it just doesn't get found.: That apostrophe is not ASCII, so you're searching for multiple bytes instead of a single one.

Upvotes: 1

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