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'

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Input and Output

Question 1

Predict the output of following program?

#include "stdio.h" int main() {     char arr[100];     printf("%d", scanf("%s", arr));     /* Suppose that input value given         for above scanf is "GeeksQuiz" */     return 1; }

A	9
B	1
C	10
D	100

Input and Output    
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Question 2

Predict output of the following program

#include <stdio.h> int main() {    printf("\new_c_question\by");    printf("\rgeeksforgeeks");    getchar();    return 0; }

A	ew_c_question geeksforgeeks
B	new_c_ques geeksforgeeks
C	geeksforgeeks
D	Depends on terminal configuration

Input and Output    
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Question 3

#include <stdio.h> int main() {   printf(" \"GEEKS %% FOR %% GEEKS\"");   getchar();   return 0; }

A	“GEEKS % FOR % GEEKS”
B	GEEKS % FOR % GEEKS
C	\"GEEKS %% FOR %% GEEKS\"
D	GEEKS %% FOR %% GEEKS

Input and Output    
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Question 4

#include <stdio.h> // Assume base address of "GeeksQuiz" to be 1000 int main() {    printf(5 + "GeeksQuiz");    return 0; }

A	GeeksQuiz
B	Quiz
C	1005
D	Compile-time error

Input and Output    
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Question 5

Predict the output of the below program:

#include <stdio.h> int main() {     printf("%c ", 5["GeeksQuiz"]);     return 0; }

A	Compile-time error
B	Runtime error
C	Q
D	s

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Question 6

Predict the output of below program:

#include <stdio.h> int main() {     printf("%c ", "GeeksQuiz"[5]);     return 0; }

A	Compile-time error
B	Runtime error
C	Q
D	s

Input and Output    
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Question 7

Which of the following is true

A	gets() can read a string with newline chacters but a normal scanf() with %s can not.
B	gets() can read a string with spaces but a normal scanf() with %s can not.
C	gets() can always replace scanf() without any additional code.
D	None of the above

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Question 8

Which of the following is true

A	gets() doesn't do any array bound testing and should not be used.
B	fgets() should be used in place of gets() only for files, otherwise gets() is fine
C	gets() cannot read strings with spaces
D	None of the above

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Question 9

What does the following C statement mean?

scanf("%4s", str);

A	Read exactly 4 characters from console.
B	Read maximum 4 characters from console.
C	Read a string str in multiples of 4
D	Nothing

Input and Output    
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Question 10

#include<stdio.h> int main() {     char *s = "Geeks Quiz";     int n = 7;     printf("%.*s", n, s);     return 0; }

A	Geeks Quiz
B	Nothing is printed
C	Geeks Q
D	Geeks Qu

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Question 11

Predict the output of following program?

#include <stdio.h> int main(void) {    int x = printf("GeeksQuiz");    printf("%d", x);    return 0; }

A	GeeksQuiz9
B	GeeksQuiz10
C	GeeksQuizGeeksQuiz
D	GeeksQuiz1

Input and Output    
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Question 12

Output of following program?

#include<stdio.h> int main() {     printf("%d", printf("%d", 1234));     return 0; }

A	12344
B	12341
C	11234
D	41234

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Question 13

What is the return type of getchar()?

A	int
B	char
C	unsigned char
D	float

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Question 14

Normally user programs are prevented from handling I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instructions privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction. Which one of the following is true for a CPU with memory mapped I/O?

A	I/O protection is ensured by operating system routine (s)
B	I/O protection is ensured by a hardware trap
C	I/O protection is ensured during system configuration
D	I/O protection is not possible

Input and Output    GATE-CS-2005    
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Question 15

Which of the following functions from “stdio.h” can be used in place of printf()?

A	fputs() with FILE stream as stdout.
B	fprintf() with FILE stream as stdout.
C	fwrite() with FILE stream as stdout.
D	All of the above three - a, b and c.
E	In “stdio.h”, there’s no other equivalent function of printf().

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