Difference between getc(), getchar(), getch() and getche()

All of these functions read a character from input and return an integer value. The integer is returned to accommodate a special value used to indicate failure. The value EOF is generally used for this purpose.

getc():
It reads a single character from a given input stream and returns the corresponding integer value (typically ASCII value of read character) on success. It returns EOF on failure.

Syntax:

int getc(FILE *stream); 

Example:

// Example for getc() in C #include <stdio.h> int main() {    printf("%c", getc(stdin));    return(0); }

Input: g (press enter key)
Output: g 

getchar():
The difference between getc() and getchar() is getc() can read from any input stream, but getchar() reads from standard input. So getchar() is equivalent to getc(stdin).

Syntax:

int getchar(void); 

Example:

// Example for getchar() in C #include <stdio.h> int main() {    printf("%c", getchar());    return 0; }

Input: g(press enter key)
Output: g 

getch():
getch() is a nonstandard function and is present in conio.h header file which is mostly used by MS-DOS compilers like Turbo C. It is not part of the C standard library or ISO C, nor is it defined by POSIX (Source: http://en.wikipedia.org/wiki/Conio.h)
Like above functions, it reads also a single character from keyboard. But it does not use any buffer, so the entered character is immediately returned without waiting for the enter key.
Syntax:

int getch();

Example:

// Example for getch() in C #include <stdio.h> #include <conio.h> int main() {    printf("%c", getch());      return 0; }

Input:  g (Without enter key)
Output: Program terminates immediately.
        But when you use DOS shell in Turbo C, 
        it shows a single g, i.e., 'g'

getche()
Like getch(), this is also a non-standard function present in conio.h. It reads a single character from the keyboard and displays immediately on output screen without waiting for enter key.

Syntax:

int getche(void); 

Example:

#include <stdio.h> #include <conio.h> // Example for getche() in C int main() {   printf("%c", getche());   return 0; }

Input: g(without enter key as it is not buffered)
Output: Program terminates immediately.
        But when you use DOS shell in Turbo C, 
        double g, i.e., 'gg'