Format Specifier in C

Format specifier in C is a String, starting with ‘%’ symbol that specifies the type of data that is being printed using printf() or read using scanf().

For example: In the following statement the %d is a format specifier that specifies that the data type of the variable num is int.

printf("%d", num);

Format Specifier

Specifier	Description
%c	It is used for unsigned character
%s	It is used for strings
%d	It is used for signed integer, which means it can hold positive as well as negative integers.
%f	It is used for floating point values such as 16.5, 19.67 etc.
%Lf	long double
%hi	signed short
%hu	unsigned short
%i	a decimal integer (detects the base automatically)
%o	Used for octal numbers
%x	Used for hexadecimal integer
%p	an address (or pointer)
%u	int unsigned decimal
%e	a floating point number in scientific notation. It is also known as Mantissa or Exponent.
%E	same as %e

Example 1: Character format specifier %c

#include <stdio.h>
int main() {
  char ch = 'A';
  char ch2 = 'r';
  printf("Lower case character: %c",ch);
  printf("\nUpper case character: %c",ch2);
  return 0;
}

Output:

Example 2: String format specifier %s

#include <stdio.h>
int main() {
  char str[20];
  printf("Enter a String: ");
  scanf("%s", str);
  printf("User Entered: %s", str);
  return 0;
}

Output:

Example 3: Integer format specifier %d

Here, we are taking the input from the user and displaying the same number as output. User is asked to enter an integer number so are using %d specifier. The same %d specifier is used while printing the input number.

#include <stdio.h>
int main() {
  int number;
  printf("Enter a Number: ");
  //%d format specifier for integer
  scanf("%d", &number);
  printf("Number entered by user: %d", number);
  return 0;
}

Output:

Example 4: Float format specifier %f

To print the number value with the decimal points, we are using %f format specifier.

#include <stdio.h>
int main() {
  float number =15.55;
  printf("%f",number);
  return 0;
}

Output:

15.550000

Example 5: Octal format specifier %o

Here we are using octal format specifier %o to convert a decimal value to an octal value. In the following example, we just used the format specifier %o to print the octal equivalent value of the given decimal number.

#include <stdio.h>
int main() {
  int num = 45;
  printf("Octal equivalent of int %d is: %o", num, num);
  return 0;
}

Output:

Example 6: Hexadecimal format specifier %x

This is similar to the example above. In this example, we are using format specifier %x to print the hexadecimal value of the given decimal number.

#include <stdio.h>
int main() {
  int num = 45;
  printf("Hexadecimal equivalent of int %d is: %x", num, num);
  return 0;
}

Output: