Question

I want to start off by saying that I have almost no experience with C++ but I am taking a college class for it this semester and was just sort of messing around so that I am a little better prepared for the class. I know a good amount of Java but almost no C++.

Basically, I want to make some integers part of a string that will go into a string 2D Array. Then I want to print out just to make sure that everything is in the array…I realize that the second for loop isn’t really necessary but I put it there anyway.

My problem is that I keep getting an error message when trying to do:

myArray[i][j] = "(" << i << "," << j << ")";

Specifically, it tells me:

error: invalid operands of types 'const char*' and 'const char [2]' to binary 
       'operator+'

I don’t understand this error nor do I know how to fix it…

Here is what I have.

int height = 5;
int width = 5;
string myArray[height][width];

for (int i = 0; i < height; ++i) {
    for (int j = 0; j < width; ++j) {
        myArray[i][j] = "(" << i << "," << j << ")";
    }
}

for (int i = 0; i < height; ++i) {
    for (int j = 0; j < width; ++j) {
        cout << myArray[i][j] << "  ";
    }
}

I just want to know how to fix the error and then I would also like to know specifically why I am getting said error. Thanks!

Answer 1

You get the error because that’s not the way to concatenate strings in C++. But the message is strange, since you appear to be using operator << and not operator +.

Regardless, use a std::stringstream.

std::stringstream ss;
ss << "(" << i << "," << j << ")";
myArray[i][j] = ss.str();