如何将字符添加到字符串中

Question

So I am creating an hangman game and want to add a char into a string. I want to add a char of guess to the gatherguess string until the gatherguess matches hangman. Feel free to add some helpful tips to my code that will make me better. Also if it would be more then nice if you can also give me some sample code with dynamic memory allocation.

#include <stdio.h>
#include <string.h>
#include <iostream>     // std::cout

#include <stdio.h>
#include <string.h>
#include <iostream>     // std::cout
#include <algorithm>    // std::for_each
#include <vector>
#include <set>
#include <string>
bool isitdone(std::string foo, std::string hang){
    return foo == hang ? true : false ;
}

int main(){
    std::string hangman;
    char guess;
    std::string gatherguess; //Get the letters guessed.
    std::cin >> hangman; //Player enter the word to guess.
    bool checkstatement; // Check to see if game is over.

    for(int i =0; i < 10; ++i) {
        std::cin >> guess; //Individual characters to guess
        std::string doo;
        int wordsin;
        doo = hangman;

        int y;
        if(doo.rfind(guess) != std::string::npos) {
            std::cout << "Right " << guess << " Is in the word"  << std::endl;

            std::cout << std::endl;

            checkstatement = isitdone(gatherguess,doo);// I want to add guess char into gatherguess 
            //then check to see if gatherguess is equal to the word then the game will be complete
            if(checkstatement == true) {
                    return 0;
            }
        } else {
            std::cout << "Wrong" << std::endl;
        }
    }
    return 0;
}

Answer 1

First of all, you should initialize gatherguess with enough placeholder characters:

auto hangman = std::string{};
std::cin >> hangman;

auto gatherguess = std::string{hangman.size(), '_'};

Now you can simply overwrite the '_' characters.

auto pos = hangman.find(guess)
if(pos != std::string::npos) {
    // ...

    do {
        gatherguess[pos] = guess;   // overwrite
        pos = hangman.find(guess, pos); // find next ocurrence
    } while(pos != std::string::npos)

    // ...
}

Answer 2

I made some changes on your code. It contains some pieces of advice as comment.

//#include <stdio.h> // Do not include a library if you don not use it, because it makes the performance worse.
//#include <string> // Do not include a library if you don not use it, because it makes the performance worse.
#include <iostream>     // std::cout
//#include <stdio.h> // It is pointless to include a library twice.
//#include <string.h>
//#include <iostream>     // std::cout
//#include <algorithm>    // std::for_each
//#include <vector> // Do not include a library if you don not use it, because it makes the performance worse.
//#include <set> // Do not include a library if you don not use it, because it makes the performance worse.
#include <string>

bool isitdone(const std::string& foo, const std::string& hang){ // Passing argument by const reference makes performance much better.
    return foo == hang ? true : false ; // Indenting makes the code much more readable.
}

int main(){
    const int N=10; // Store constant number in constant variable, because you can change its' value later easily.
    std::string hangman;
    char guess;
    std::string gatherguess; //Get the letters guessed.
    std::cin >> hangman; //Player enter the word to guess.
    bool checkstatement; // Check to see if game is over.

    for(int i =0; i < N; ++i)
    {
        std::cin >> guess; //Individual characters to guess
        std::string doo;
        int wordsin;
        doo = hangman;
        int y;
        if(doo.rfind(guess) != std::string::npos)
        {

            std::cout << "Right " << guess << " Is in the word"  << std::endl;

            std::cout << std::endl;

            checkstatement = isitdone(gatherguess,doo);// I want to add guess char into gatherguess
            //then check to see if gatherguess is equal to the word then the game will be complete
            if(checkstatement == true)
            {
                return 0;
            }
        } else
        {
            std::cout << "Wrong" << std::endl;
        }
    }
    return 0;
}

I think there is a logical mistake in your program. What happens if a word contains more than 10 different characters? Do not count if the tipp is right.

You can add a char to a string this way:

#include <iostream>
#include <string>

int main(){
    std::string str="123";
    str+='4';
    std::cout<<str<<std::endl;

    return 0;
}