Transforming Integers into Chars

I have a file IO where I read from file A.txt which contains an integer (int Bla).
Later in the program, I want to save into a file, named after the integer in file A.txt, I
write:

strcat(Bla,".txt");

ofstream w_file(Bla);
w_file<<...;
w_file.close();

I know this doesn't work but what I want to know is how to make a char of in Bla, so that I can use it to save my file.
Thanks!

itoa()...

If you only need to use one digit integers, you can cast the char into an int. Then, subtract 48 from the int value. If the value is more than one int, you can use the same idea but it will be more complicated.

Thank you all very much!

itoa didn't work, but that's because I'm using unix, so I found an unix-itoa on the web, when someone is interested, I'll post it.