Changing characters in a string.

This is a discussion on Changing characters in a string. within the C++ Programming forums, part of the General Programming Boards category; Hi, Iím trying to write a simple program to change the charters in a string, but for some reason I ...

  1. #1
    Registered Abuser Loic's Avatar
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    Changing characters in a string.

    Hi, Iím trying to write a simple program to change the charters in a string, but for some reason I cant get it to work, and I cant for the life of me work out why, im fairly new to c++ so im sure must be doing some stupid mistake, but if someone could have a look at this code, and give me a pointer or 2, it would be greatly appreciated.

    Basicly all i want it to do is change all the "x"'s to an upper case X...

    it will change the first one, but thats it...

    Code:
    #include <cstdlib>
    #include <iostream>
    
    using namespace std;
    
    int main(int argc, char *argv[])
    {
        string sen;
        cout << "Please enter a sentence ";
        getline (cin, sen);
        string::size_type senx = sen.find( "x" );
        if (senx >=0)
        {
                 sen[senx] = toupper (sen[senx]);
                 string::size_type senx = sen.find( "x" );
        }
    
        cout << sen << endl;
    
        system("PAUSE");
        return EXIT_SUCCESS;
    }

  2. #2
    Registered User
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    You don't have a loop. You are using if, but if doesn't loop, it just runs once. You probably want a while loop.

  3. #3
    Registered Abuser Loic's Avatar
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    Yeah, i realized that,..

    but i got it working, now i am just trying to compact it a bit, i have a few ideas, but just wanted to get some advice...

    Code:
    #include <cstdlib>
    #include <iostream>
    
    using namespace std;
    
    int main(int argc, char *argv[])
    {
        string sen;
        cout << "Please enter a sentence ";
        getline (cin, sen);
        // Change X
        int countx = 0;
        for (int i = 0; i < sen.size(); ++i)
        if (sen[i] == 'x')
              ++countx;
        int x=0;
        while (x <= countx)
        {
              string::size_type senx = sen.find( "x" );
              sen[senx] = toupper (sen[senx]);
              x++;
        }
        // Change Y
        int county = 0;
        for (int i = 0; i < sen.size(); ++i)
        if (sen[i] == 'y')
              ++county;
        int y=0;
        while (y <= county)
        {
              string::size_type senx = sen.find( "y" );
              sen[senx] = toupper (sen[senx]);
              y++;
        }
        // Change Z
        int countz = 0;
        for (int i = 0; i < sen.size(); ++i)
        if (sen[i] == 'z')
              ++countz;
        int z=0;
        while (z <= countz)
        {
              string::size_type senx = sen.find( "z" );
              sen[senx] = toupper (sen[senx]);
              z++;
        }
        // output    
        cout << sen << endl;
    
        system("PAUSE");
        return EXIT_SUCCESS;
    }

  4. #4
    Lean Mean Coding Machine KONI's Avatar
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    Maybe something along the line of:

    Code:
        char replace[] = {'x', 'y', 'z'};
        int i, pos;
        string sen;
    
        cout << "Please enter a sentence ";
        getline (cin, sen);
    
        for (i = 0; i < sizeof(replace); i++)
        {
            while ((pos = sen.find(replace[i])) != string::npos)
            {
                sen[pos] = toupper(sen[pos]);
            }
        }
        cout << sen;
    replace is a character array that contains all the characters you want to capitalize. I first iterate over all the characters inside that array, to have them all treated. Then I replace the characters as long as I found one (sen.find returns string::npos if it couldn't find any occurence).
    Last edited by KONI; 03-30-2007 at 06:17 AM.

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