3. Types of Input and Output Functions in C

In C, input refers to feeding information or data in the program. On the other hand, output refers to writing the data and information on any printer file and displaying it on the screen. A standard library .i.e stdio.h header file is available in the C language for reading any input and generating the output to be displayed on the console.
Input and Output Functions in C language are classified in to types.
A. Formatted Functions
B. Unformatted Functions

A. Formatted Functions.
The C Language comes with standard input output functions printf() and scanf() so that we can perform formatted input and output in a C program. C Language performs formatted input and output operations using standard input output formatted functions which is available in standard library file stdio.h
The formatted functions basically present or accept the available data (input) in a specific format. The standard library stdio.h in C contains various functions for the input-output operations. The scanf() and printf() functions help a programmer to format the functions in their desired format. Programmer use the formatted input and output functions for taking single or multiple inputs from the user at console.These formated functions also allow user to display single or multiple values.

Lets Learn Some Important formated input output function in C Language.

i.printf():    C Program use this function for displaying a single or multiple values in the form of output for the user at console.
The printf() function basically gets defined in the header file stdio.h, and Programmer use it for showing the standard output at console. The printf function in C program is use to display or print the value of variable or any sample text.
This function is a part of the C language standard library "stdio.h" and allow programmer to format output in various ways.
Syntax of printf:  printf("format String",args);

ii. scanf():
The scanf() Library function in C programming is a powerful tool for reading input from the user or from a file and storing it in variables.
The scanf() function is a standard Library function in C Programming used to reads all datatypes from the(user) standard input stream stdin into the locations(variables) given by the entries in argument-list. Each argument must list be a pointer to a variable with a type that corresponds to a type specifier in format-string.
By specifying format specifiers in the format string, you can read input values of different types, such as character,strings,integers, floating-point numbers.
The scanf in C accepts two values: formatted string and memory location of variables in which we wish to store input data obtained from the user.
Synatx: int scanf ( const char * format_string, &variable );
The two parameters passed to scanf function are.
format_string:
Like printf() function scanf() has format specifier or format string. For example, %c is used for character value, %d is used for integer numbers, etc.
&variable:
To store input data, scanf needs to known the memory address or location of a variable. The ampersand (&) operator or address of the operator is used to know memory address or a variable location.
For example, &salary is the address of salary.The value taken from the input is stored in the location pointed by the variable. This is why we pass the variable address in which we want to store the value.

B.  Unformatted Functions in C :

C Programming language has following types of unformatted function
a. getchar()
b. putchar()
c.gets()
d. puts()
e. getc().
a. getchar(): is the most basic input function in C Programming Language that reads a single character from the standard input stream stdin(i.e Keyboard device), regardless of what it is, and returns it to the program. This standard library function is used when single character input is required from the user.
It is defined inside the standard input output stream <stdio.h> header file.
The standard input stream provides multiple functions to take the input from the user at the run time of a program.
The function reads the next available character from the screen and returns it as an integer. Programmer can use getchar() function inside a loop to read more than one character from the screen .
Syntax of getchar() in C :

int getchar(void);

getchar() function does not take any parameters. Return Value The input from the standard input is read as an unsigned char and then it is typecast and returned as an integer value(int). EOF is returned in two cases: When the file end is reached When there is an error during the execution

b. putchar():The putchar is a function in the C programming language that writes a single character to the standard output stream, stdout.
The putchar function is specified in the C standard library header file <stdio.h>.
This function puts the passed character on the screen and returns the same character. This function displays only single character at a time. You can use this function in the loop in case you want to display more than one character on the screen.
Its syntax is as follows:

int putchar (int character);

The int character parameter for this function is mandatory, which is the character to be printed or written to stdout or console.if the writing is successful, the argument character is returned. Otherwise, end-of-file is returned.
Check the following example −