Replace function

Hi I am trying to write a little program that will replace a charter in a string, for example if there is a “5”, replace it with a “?” I have been playing around with the “replace” function but cant get it to work.

Code:

char rep[] = {5};
    int i, pos;
    string sen;

    cout << "Please enter a sentence ";
    getline (cin, sen);

    for (i = 0; i < sizeof(rep); i++)
    {
        while ((pos = sen.find(repl[i])) != string::npos)
        {
            sen[pos] = replace  // This is where I am lost? 
   	}
    }
    cout << sen;

I have read every page that i cam find on google, and i am still lost... Please help!

The replace function is a member function of the string class, so you should probably be calling it like you call find(). Then it's just a matter of putting in the right parameters.

Originally Posted by Daved

The replace function is a member function of the string class, so you should probably be calling it like you call find(). Then it's just a matter of putting in the right parameters.

Cheers mate, I got it working,

Code:

    int i, pos;
    string sen;

    cout << "Please enter a sentence ";
    getline (cin, sen);

    char replace = 48;
    string s2 = "?";
    for (i = 0; i < sizeof(replace); i++)
    {
        while ((pos = sen.find(replace)) != string::npos)
        {
            sen.replace( pos, 1, s2 );
        }
    } 
    cout << sen;

But at the moment it can only get it to change one character, "0" if i wanted it to change 0,1,2,3,4,5,6,7,8,9

would i change

Code:

    char replace = 48;

to (i know this doesn't work)

Code:

char replace = 48,49,50,51,52,53,54,55,56,57;

how do it do it? or would i have to copy that over and over again?

All good, worked it out

>> All good, worked it out
Great! Feel free to post your solution so if somebody searches with the same problem they can benefit.

>> char replace = 48;
There's no reason to use 48 here. It is a magic number and not everybody will know what it stands for. When you want to specify a single character, just put it in single quotes:

Code:

char replace = '0';

That will work no matter what the character set being used is.

Originally Posted by Daved

>> All good, worked it out
Great! Feel free to post your solution so if somebody searches with the same problem they can benefit.

>> char replace = 48;
There's no reason to use 48 here. It is a magic number and not everybody will know what it stands for. When you want to specify a single character, just put it in single quotes:

Code:

char replace = '0';

That will work no matter what the character set being used is.

No worries mate

Code:

    char replaceNUM[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}; 
    int i, pos;
    string sen;

    cout << "Please enter a sentence " << endl;;
    getline (cin, sen);
    
    string newChar = "?";
    for (i = 0; i < sizeof(replaceNUM); i++)
    {
        while ((pos = sen.find(replaceNUM[i])) != string::npos)
        {
            sen.replace( pos, 1, newChar );
        }
    }

If anyone wants more info on the "replace" have a read of this http://www.cppreference.com/cppstring/replace.html i found it to be quite useful

Code:

endl;;

Double semicolons might look nice, but they're unnessesary.

BTW, pos should probably be declared as

Code:

string::size_type pos;

Note also, that the string find method has useful relatives, for example find_first_of:

Code:

std::string replaceChars("123456789");
    std::string newChar = "?";
    
    while ((pos = sen.find_first_of(replaceChars)) != std::string::npos)
    {
        sen.replace( pos, 1, newChar );
    }