C Library Functions
C Standard library functions or simply C Library functions are inbuilt functions in C programming.
The prototype and data definitions of these functions are present in their respective header files. To use these functions we need to include the header file in our program. For example,
If you want to use the printf() function, the header file <stdio.h> should be included.
LIST OF MOST USED HEADER FILES IN C PROGRAMMING LANGUAGE:
Header file | Description |
| stdio.h | This is standard input/output header file in which Input/Output functions are declared |
| conio.h | This is console input/output header file |
| string.h | All string related functions are defined in this header file |
| stdlib.h | This header file contains general functions used in C programs |
| math.h | All maths related functions are defined in this header file |
Unformatted Input/Output function
getchar() Function
The getchar() function reads character type data form the input. The getchar() function reads one character at a time till the user presses the enter key.
Example:
#inclide<stdio.h>
#include<conio.h>
int main()
{
char a;
printf("Enter a character : ");
a= getchar();
printf("\nEntered character : %c",a);
return 0;
}
Output:- Enter a character : r
Entered character : r
putchar() Function
putchar() function prints only one character at a time.
Example
#include<stdio.h>
#include<conio.h>
int main()
{
char a='R';
putchar(a);
return 0;
}
Output:- R
getch() Function
The getch() function reads the alphanumeric character input from the user. But, that the entered character will not be displayed.
Example:
#include<stdio.h>
#include<conio.h>
int main()
{
printf("hii, press any alphanumeric character to exit ");
getch();
return 0;
}
Output:- hii,press any alphanumeric character to exit
getche() Function
getche() function reads the alphanumeric character from the user input. Here, character you entered will be echoed to the user until he/she presses any key.
Example:
#include<stdio.h>
#include<conio.h>
int main()
{
printf("Hii,press any alphanumeric character or symbol to exit");
getche();
return 0;
}
Output:
Hii,press any alphanumeric character or symbol to exit
a
putch() Function
The putch() function prints any alphanumeric character.
Example:
String I/O Functions
gets() Function
The gets() function can read a full string even blank spaces presents in a string. But, the scanf() function leave a string after blank space space is detected. The gets() function is used to get any string from the user.
Example:
#include <stdio.h>
#include <conio.h>
int main()
{
char a[25];
printf("Enter a string : ");
gets(a);
printf("\n%s ,New Delhi ",a);
return 0;
}
Output: Enter a string : IIT Dwarka
IIT Dwarka ,New Delhi
puts() Function
The puts() function prints the charater array or string on the console. The puts() function is similar to printf() function, but we cannot print other than characters using puts() function.
Example:
#include <stdio.h> //header file section
#include <conio.h>
int main()
{
char a[25];
printf("Enter your Name : ");
gets(a);
puts(a);
return 0;
}
Output: Enter your Name: itesm
itesm
Formatted Input/Output function
Scanf()
In the C programming language, scanf is a function that reads formatted data from stdin (i.e, the standard input stream, which is usually the keyboard, unless redirected) and then writes the results into the arguments given.
The scanf function uses the same placeholders as printf:
- int uses %d
- float uses %f
- char uses %c
- strings uses %s
printf() function
The printf() function is used for output. It prints the given statement to the console.
The syntax of printf() function is given below:
syntax:- printf("format string",argument_list);
Example:
#include <stdio.h>
int main()
{
char ch = 'A';
char str[20] = "iitditnotes.blogspot.com";
float flt = 10.234;
int no = 15;
double dbl = 2.123456;
printf("Character is %c \n", ch);
printf("String is %s \n" , str);
printf("Float value is %f \n", flt);
printf("Integer value is %d\n" , no);
printf("Double value is %lf \n", dbl);
return 0;
}
Output:
Character is A
String is iitditnotes.blogspot.com
Float value is 10.234000
Integer value is 15
Double value is 2.123456
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