You'd need to provide a bit more information. You can't have variables be part of an identifier name and have them be replaced, but you can use variables in expressions like you are up there. The only issue I see is that "2c" isn't a valid name because it starts with a number.
You all understood it very wrong! He meant this: pictureBox[i]->Load(/*the value of the variable 2c*/".gif");
It is possible if the value of that variable is a std::string: pictureBox[i]->Load(2c+".gif");
But, of course, the name of the variable cant start with a number!