C : include string before the vowels in a sentence-CodePudding

I'm a beginner in c and I'm training on exercises.

I'm stuck on one part. I would like to insert the string "CH" in front of each vowel in a sentence.

I first tried using string::replace, but it was not the best idea. I would like to use string::insert to do this.

However, I can't seem to use it properly in a loop to tell it that the [i] is the desired position

Do you have any advice for me?

    string message = "you have a secret message to decrypt";
    string newMessage = "";
    string InsertMessage = "CH";

    for (int i = 0; i < message.length(); i  ) {
        if (
            message[i] == 'a' ||
            message[i] == 'e' ||
            message[i] == 'i' ||
            message[i] == 'o' ||
            message[i] == 'u' ||
            message[i] == 'y')
        {
            //newMessage = message.replace(i, 1, InsertMessage);
            newMessage = message.insert(i, InsertMessage);
        }
    }

    cout << newMessage << endl;

    return 0;

CodePudding user response：

This statement

newMessage = message.insert(i, InsertMessage);

does not make a sense at least because it changes the original string message.

I can suggest the following approach shown in the demonstration program below.

#include <iostream>
#include <string>
#include <iterator>
#include <algorithm>

int main()
{
    std::string message = "you have a secret message to decrypt";
    std::string newMessage;
    std::string InsertMessage = "CH";
    const char *vowels = "aeiouy";

    auto n = std::count_if( std::begin( message ), std::end( message ),
        [vowels]( const auto &c ) { return std::strchr( vowels, c ); } );

    newMessage.resize( message.size()   n * InsertMessage.size() );

    std::string::size_type pos = 0;
    do
    {
        auto i = message.find_first_of( vowels, pos );

        if (i == std::string::npos)
        {
            newMessage  = message.substr( pos );
            pos = i;
        }
        else
        {
            newMessage  = message.substr( pos, i - pos );
            newMessage  = InsertMessage;
            pos = i;
            newMessage  = message[pos  ];
        }
    } while( pos != std::string::npos );

    std::cout << newMessage << '\n';
}

The program output is

CHyCHoCHu hCHavCHe CHa sCHecrCHet mCHessCHagCHe tCHo dCHecrCHypt

CodePudding user response：

Thanks for your answers, I'll work on it :)