Update ex7_23_24_25.cpp

ex7.24
1.a constructor that takes values for height and width and initializes the contents to hold the given number of blanks;
In my oponin ,"takes values for height and width' mean  the number of parameters is  two.

2. a constructor that takes values for height, width, and a character to use as the contents of the screen.
I think the characters is fill the screen