C++ :: Print Chars As Keys Are Hit?

I found this method

Code:
TCHAR win_getch()

(below) on a website which is used for printing the characters as the keys on keyboard are hit i-e without hitting the ENTER key. This method is used in a while loop like this

Code:
while ((c = win_getch()) != 13)
{}

I wanted to know why is the character compared to

Code:
13
i-e
Code:
if((c = win_getch()) != 13) then do something

Code:
/**
* This function will simulate the getch() function from conio.h.
* Note that this does not work for special keys like F1-F12, arrow keys,
* even the ESC key does not seem to work with this function.
* @return TCHAR read from input buffer.
*/
TCHAR win_getch() {
DWORD mode;
TCHAR theChar = 0;

[code]....