Changing characters in a string.

Hi, I’m 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;
}

---

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.

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;
}

---

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).