Getting the first numbers from a string

[toefraz]

Hey, guys. I'm writing a program that searches through a census file and returns a name for a inputted rank. I've been trying to get this function to parse the rank string to only get only the digits in the first 4 places so that it would only return a string whose value ranges from 0 - 9999. Here's what I have so far, and it's not done by any means:

void rankSearch()
{
    string str1 = "", str2 = "";
 
    int rank, count = 0, leave;
 
    cout << "Please enter a ranking (1-1000):  ";
    getline(cin >> ws, str1);
    do
    {
    for(count = 0; count < 4; count++)
        {
            if(isdigit(str1.at(count)))
                str2.push_back(str1.at(count));
            else
                break;
        }
 
        rank = atoi(str1.c_str());
 
        if(rank <= 0 || rank > 1000)
        {
            cout << "Invalid rank. Please try again:  ";
            getline(cin >> ws, str1);
            leave = 0;
        }
        else
            leave = 1;
    }while(leave == 0);
 
    cout << "Names for that rank are:  " << rank << endl; //This doesn't actually do anything yet. Just for testing purposes.
 
}

Please tell me what I'm doing wrong, because the program crashes if I don't enter a 4 digit number.

[Ganon11]

One thing I see is you are mixing getline with cin >> statements. Shouldn't it be:

getline(cin, str1);

Next, after you setup str2 to hold all the digits, you use atoi on str1? Then what is the point of str2?

[toefraz]

I had it where it would change str2 into a char array, then just use atoi on the the char array, but i changed it to just use a .c_str() on str1. I just didn't remove the str2. I got it working finally. I just had to fill up the string past 4 characters otherwise it would try to access out-of-bound data.

[toefraz]

Here's my final function. Tell me if you think there is a better way to go about doing this:

void rankSearch()
{
    string str;
    int rank = 0, count = 0, leave = 0;    
 
    cout << "Please enter a ranking (1-1000):  ";
 
    do
    {
        getline(cin >> ws, str);
        str += "fillfillfill"; //Fill up the string to prevent issues if there are less than 4 characters in it.
 
        for(count = 0; count < 4; count++)
        {
            if(str.at(0) == '0')
            {
                rank = -1;
                str.erase((count + 1), str.length());
                break;
            }
            if(isdigit(str.at(count)))
                continue;
            else
            {
                rank = -1;
                str.erase((count + 1), str.length());
                break;
            }
        }
 
        rank = atoi(str.c_str());
 
        if(rank <= 0 || rank > 1000)
        {
            cout << "Invalid rank. Please try again:  ";
            leave = 0;
        }
        else
            leave = 1;
    }while(leave == 0);
 
    cout << endl;
    cout << "Names in rank " << rank << " are:  " << endl << endl;
        for(count = 0; count < 10; count++)
        cout << "   " << (count * 10) + 1900 << ":  " << info[count][rank - 1][0] << " and "
             << info[count][rank - 1][1] << endl;
 
}

[Ganon11]

Well, I don't know exactly what your function is doing, now do I know why (or how) getline(cin >> ws, str) is working. BUT, if your function works, it works. Are there different ways to do this? Probably, but the most important thing about a program is that it works.