Thread: A basic syntax question

You use a stringstream:

Code:

#include <iostream>
#include <sstream>

int main() {
	int x = 5, y = 2;

	std::stringstream s;

	// Convert 'x' and 'y' to strings and concatenate them
	s << x << y;

	// Get full string with str() method
	std::cout << "'" << s.str() << "'" << std::endl;
	
	return 0;
}

Awesome, I love you!

But one more thing. How can I convert it back into an integer.

Sorry, I feel like I should be looking this stuff up myself, but I'm not on my best game today.

you can use atoi()

Code:

int value = atoi(s.str().c_str());

Will you love me too?

Code:

#include <iostream>
#include <sstream>

int main() {
	int x = 5, y = 2;

	std::stringstream s;

	// Convert 'x' and 'y' to strings and concatenate them
	s << x << y;

	// Get full string with str() method
	std::cout << "'" << s.str() << "'" << std::endl;

	int z;
	// Extract an integer
	s >> z;
	std::cout << z << std::endl;
	
	return 0;
}

More info: http://www.cplusplus.com/ref/iostream/stringstream/

Bump because you mightn't have seen my reply.

This "something small" is not exactly something you commonly need. Usually what you do with numbers is add them, subtract them, divide them and so on. These things are easy to do in C++.
Concatenating numbers is not something you do often. You do that with strings. With strings, concatenation is easy: just use the + operator.
So to achieve what you want, you have to convert the numbers to strings, concatenate them, then convert the resulting strings back to a number.

It's the same in PHP, by the way, except that, due to PHP's weak typing, these conversions are implicit. Try it out:

Code:

$a = 1;
$b = 2;
$c = $a . $b; // Implicitly convert the values of $a and $b to strings.
echo get_type($c); // Echos 'string'.
$b += $c; // Implicitely convert the value of $c to int.

Thanks for all the help guys, I am actually working with an array.

I would appreciate any help with this code, it crashes onces it gets to board[8][2], I guess its probably a memory problem.

Code:

#include <iostream>
#include <sstream>
using namespace std;

int main() {                                          //begin main program
  int x = 1, y = 1;                                  //declare x and y
  int board[8][8];                                  //declare array board
  while ( y < 9 ) {                                 //loop 8 times for y
    while ( x < 9 ) {                               //loop 8 times for x
      std::stringstream c;
      c << y << x;                                 //append the values of x and y
      int tc = atoi(c.str().c_str());           //convert the result to an integer
      board[y][x] = tc;                            //set the integer value into the array
      cout<< tc;                                      //print the integer value
      cout<<  "\n\n\n";
      x = x + 1;                                    //incriment to x
    }//end first loop
    x = 1;                                           //reset x to 1
    y = y + 1;                                     //incriment to y
  }                                                      //end second loop

cout<< board[1][1] << "\n";
cout<< board[8][8] << "\n";
cout<< board[2][1] << "\n";
cout<< board[3][2] << "\n";
cout<< board[1][6] << "\n";
cin.get();
return 0;
}

sorry if the comments are bothersome, but they help me learn.

Code:

 y = y + 1;//incriment to y

This can be simplified to:

Code:

y++;

EDIT: Same for x.

Arrays are 0-based, but you treat them as 1-based.