C – printf and scanf

• printf() and scanf() functions are inbuilt library functions in C programming language which are available in C library by default. These functions are declared and related macros are defined in “stdio.h” which is a header file in C language.
• We have to include “stdio.h” file as shown in below C program to make use of these printf() and scanf() library functions in C language.

1. printf() function in C language:

• In C programming language, printf() function is used to print the “character, string, float, integer, octal and hexadecimal values” onto the output screen.
• We use printf() function with %d format specifier to display the value of an integer variable.
• Similarly %c is used to display character, %f for float variable, %s for string variable, %lf for double and %x for hexadecimal variable.
• To generate a newline,we use “\n” in C printf() statement.

Note:

• C language is case sensitive. For example, printf() and scanf() are different from Printf() and Scanf(). All characters in printf() and scanf() functions must be in lower case.

Example program for C printf() function:

C

#include <stdio.h> int main() { char ch = 'A'; char str[20] = "fresh2refresh.com"; float flt = 10.234; int no = 150; double dbl = 20.123456; 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); printf("Octal value is %o \n", no); printf("Hexadecimal value is %x \n", no); return 0; }

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

#include <stdio.h> int main() {    char ch = 'A';    char str[20] = "fresh2refresh.com";    float flt = 10.234;    int no = 150;    double dbl = 20.123456;    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);    printf("Octal value is %o \n", no);    printf("Hexadecimal value is %x \n", no);    return 0; }

Output:

Character is A String is fresh2refresh.com Float value is 10.234000 Integer value is 150 Double value is 20.123456 Octal value is 226 Hexadecimal value is 96

You can see the output with the same data which are placed within the double quotes of printf statement in the program except

• %d got replaced by value of an integer variable  (no),
• %c got replaced by value of a character variable  (ch),
• %f got replaced by value of a float variable  (flt),
• %lf got replaced by value of a double variable  (dbl),
• %s got replaced by value of a string variable  (str),
• %o got replaced by a octal value corresponding to integer variable  (no),
• %x got replaced by a hexadecimal value corresponding to integer variable
• \n got replaced by a newline.

2. scanf() function in C language:

• In C programming language, scanf() function is used to read character, string, numeric data from keyboard
• Consider below example program where user enters a character. This value is assigned to the variable “ch” and then displayed.

• Then, user enters a string and this value is assigned to the variable “str” and then displayed.

Example program for printf() and scanf() functions in C programming language:

C

#include <stdio.h> int main() { char ch; char str[100]; printf("Enter any character \n"); scanf("%c", &ch); printf("Entered character is %c \n", ch); printf("Enter any string ( upto 100 character ) \n"); scanf("%s", &str); printf("Entered string is %s \n", str); }

1 2 3 4 5 6 7 8 9 10 11 12

#include <stdio.h> int main() {    char ch;    char str[100];    printf("Enter any character \n");    scanf("%c", &ch);    printf("Entered character is %c \n", ch);    printf("Enter any string ( upto 100 character ) \n");    scanf("%s", &str);    printf("Entered string is %s \n", str); }

Output : 

Enter any character a Entered character is a Enter any string ( upto 100 character ) hai Entered string is hai

• The format specifier %d is used in scanf() statement. So that, the value entered is received as an integer and %s for string.
• Ampersand is used before variable name “ch” in scanf() statement as &ch.
• It is just like in a pointer which is used to point to the variable. For more information about how pointer works, please click here.

KEY POINTS TO REMEMBER IN C PRINTF() AND SCANF():

1. printf() is used to display the output and scanf() is used to read the inputs.
2. printf() and scanf() functions are declared in “stdio.h” header file in C library.
3. All syntax in C language including printf() and scanf() functions are case sensitive.