how to find a character and read what's before it-CodePudding

int main() {
    string getEmail;
    
    string email, firstName, lastName;
    char dot = '.';
    cout << "What is your email?" << endl;
    getline(cin, email);
    
    double pos = email.find(dot);
    firstName = //store every letter before the dot;
    cout << firstName << endl;
    return 0;
}

how can I read the email, let's say I encounter '.', I want to read the word before it. e.i, Yes.no, I find '.' and read yes and store it in a variable.

CodePudding user response：

Why is pos a double? Positions are integers. For positions in strings there is a special integer type called size_t, so your code should be

size_t pos = email.find(dot);

To get the first part of the email address you can use the substr method. It has two parameters, a position (where the substring starts) and a count (how many characters in the substring). So to get the first part of the string you say

firstName = email.substr(0, pos);

Note that if email does not contain a dot then this code will put the whole string into firstName. If you want to test for that then you do it like this

size_t pos = email.find(dot);
if (pos == string::npos)               // if no dot
    cout << "no dot in email address";

CodePudding user response：

The substr() should be the solution to this, but seems like the datatype of pos is not necessary to be a double, should be an integer.

int main()
{
    string getEmail;
    
    string email, firstName, lastName;
    char dot = '.';
    cout << "What is your email?" << endl;
    getline(cin, email);
    
    size_t pos = email.find(dot);
    firstName = email.substr(0, pos);
    cout << firstName << endl;
    return 0;
}

CodePudding user response：

You could get the string from the start to the dot. Lets suppose i is the position of the dot. You could just return [0:i] and it will get every character until the dot.