How do you return a char * two char pointer? Local variable is being returned error c++

Lets say I have a prepend function:

//for example xMessage = "apple";
//for example yMessage = "juice";
//answer should be newMessage = "applejuice"

char* concat(char *xMessage, int xSize, char* yMessage, int ySize){
     char newMessage[xSize+ySize];
     for(....){
        //copyxMessage
     }
     for(....){
        //copyYMessage
     }
    return (char *) newMessage;
}

I know I can use strings, but I can’t do it for this issue.

>Solution :

Note: I absolutely do not agree with doing this, but since you know you can use a std::string but would like to do it with raw pointers, here’s one way:

• Allocate a buffer large enough to hold xSize + ySize characters + 1 extra for the terminating \0. You do this with new[].
• std::memcpy the input strings into the allocated buffer.
• Don’t forget to delete[] the buffer after use.

#include <cstring>

char* concat(const char *xMessage, int xSize, const char* yMessage, int ySize) {
    char* newMessage = new char[xSize + ySize + 1];

    std::memcpy(newMessage, xMessage, xSize);
    std::memcpy(newMessage + xSize, yMessage, ySize);
    newMessage[xSize + ySize] = '\0';

    return newMessage;
}

Demo