Nrthugu

I am Having trouble merging two strings together in c++, here is some example code of my problem

#include<iostream>



using namespace std;



// I want to add these two strings





string str1 = "H _ l _ o";

string str2 = "_ e _ l _";



//Now if i try add these together





cout << str1 + str2 << endl;





// outputs "H _ l _ o _ e _ l _"









// i Want it to output "H e l l o"



// anyway i could do that? Thanks

First of all, I'm assuming that the spaces should not be there in your input strings, otherwise the output will look strange.

There's pre-defined merge() function or method in C++, you would have to write it yourself. This should give you some starting help (pseudo-code):

string mergeStrings(string1, string2)

{

    string output = "";  // empty string. The loop below will add to it.

    output.reserve(string1.length);   // pre-allocate memory for performance



    // add two chars per loop iteration, one from string1, one from string2:

    for(i=0; i < min(string1.length, string2.length)/2; i+=2)

    {

        output += string1[i];

        output += string2[i+1];

    }



    return output;

}

Please check using a pen and paper whether the loop boundaries are correct: There might be an "off by one" error there.

Also, you need to think about what the function should do if the input strings have different length!

The operator + between two strings creates a new string which is the concatenation of the two input strings.

You should create your own function. Here is an example where the characters "_" of str1 are replaced by the corresponding characters in str2. (it assumes str1 and str2 have the same size)

string merged = str1;

for (int i=0; i < str1.size(); ++i)

{

    if (str1[i] == '_')

            merged[i] = str2[i];

}

you can create a function that returns the merged string validating when another string is smaller than the other and using a "merge identifier" which is going to be the special character to replace, something like this:

//----------------function declaration----------------

std::string merge_strings(std::string strA, std::string strB, char mergeIdentifier);

int greater_number(int numberA, int numberB);

int smaller_number(int numberA, int numberB);



int main()

{

    std::string str1 = "H _ l _ o";

    std::string str2 = " _ e _ l _";



    std::cout << merge_strings(str1, str2, '_'); //outputs H e l l o



    return 0;

}



//-----------------function definition----------------

std::string merge_strings(std::string strA, std::string strB, char mergeIdentifier)

{

    std::string merged = "";



    int greaterIndex = greater_number(strA.size(), strB.size());

    int smallerIndex = smaller_number(strA.size(), strB.size());



    for(int currentCharIndex = 0; currentCharIndex < greaterIndex; currentCharIndex++)

    {

        if(currentCharIndex < smallerIndex)

        {

            if(strA[currentCharIndex] == mergeIdentifier)

                merged += strB[currentCharIndex];

            else if(strA[currentCharIndex] != mergeIdentifier)

                merged += strA[currentCharIndex];

        }

        else

            break;

    }



    return merged;

}





int greater_number(int numberA, int numberB){return numberA > numberB? numberA : numberB;}

int smaller_number(int numberA, int numberB){return numberA < numberB? numberA : numberB;}

If one of the strings is smaller than the other, it will merge just the size of the smaller string but you could just add the missing characters by checking which string is longer and adding the characters from the merged string size to the end of the longer string.