Input output in c

This post explains you about Input output in c programming language.

Note: In this article we are not discussing anything about file io and its functions.

Input Output in c

Input refers to inputting data to the computer. It can be achieved through various input devices. For a typical c program we can input through standard input device i.e. keyboard or we can use command line arguments or even we can input from a file.

Output refers to displaying data from computer. It can be achieved through various output devices. For a typical c program we can output through standard output device i.e. display monitor.

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How to Perform Input Output in c?

C programming provides standard header file stdio.h to How to perform Input output which contains all the required functions to perform IO.

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File Descriptors Associated in UNIX Based Systems

For performing io operations in unix based systems c opens a file descriptors viz. stdin,stdout,stderr which are defined in stdio header file.

File Descriptor	Device	Type
stdin	Keyboard	Input
stdout	Display console	Output
stderr	Display console	Error

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Functions for Input Output in c

Type	Function Name	Prototype
Input	scanf	int scanf(const char *format, params...)
	gets	char *gets(char *c)
	getchar	int getchar(void)
Output	printf	int printf(const char *format, params...)
	puts	int puts(const char *c)
	putchar	int putchar(int c)

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Input Output in c with functions

scanf in c

scanf in c is used to perform input operation. It returns an int of number of characters it read. Inorder to read a value we have to pass the symbol associated with the datatype ( to know more on datatypes and the symbols associated read this article) and the address of variable.

Prototype of scanf

#include<stdio.h>
int scanf(const char *format, params...)

Example program for scanf

#include<stdio.h>
int main(int argc, char const *argv[])
{
	int var;
	scanf("%d",&var);
	return 0;
}

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gets in c

gets in c is used to read a string ( array of character ). It takes a pointer to array of character. It stops reading until EOF ( End Of File ) is encountered.

Prototype of gets

#include<stdio.h>
char *gets(char *c)

Example program for gets

#include<stdio.h>
int main(int argc, char const *argv[])
{
	char s[100];
	gets(s);
	gets( s );
	puts(s);
	return 0;
}

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getchar in c

getchar in c is used to read a character. It stores the read input at an int.

Prototype of getchar

#include<stdio.h>
int getchar(void)

Example program for getchar

#include<stdio.h>
int main(int argc, char const *argv[])
{
	int x=getchar();
	putchar(x);
	return 0;
}

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printf in c

printf in c is used to output formatted data to the console.

It returns an int of number of characters outputted to console. Inorder to output a variable we have to pass the symbol associated with the datatype ( to know more on datatypes and the symbols associated read this article) and the of variable as parameter.

Prototype of printf

#include<stdio.h>
int printf(const char *format, params...)

Example program for printf

#include<stdio.h>
int main(int argc, char const *argv[])
{
	printf("Hello world");
	return 0;
}

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puts in c

puts in c is used to output a string to the console.

Prototype of puts

#include<stdio.h>
int puts(const char *c)

Example program for puts

#include<stdio.h>
int main(int argc, char const *argv[])
{
	char s[100];
	gets(s);
	gets( s );
	puts(s);
	return 0;
}

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putchar in c

putchar in c is used to output a single character to console.

Prototype of puts

#include<stdio.h>
int putchar (int c)

Example program for putchar

#include<stdio.h>
int main(int argc, char const *argv[])
{
	int x=getchar();
	putchar(x);
	return 0;
}

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