Format Specifiers in C

The Format specifier is a string used in the formatted input and output functions. The format string determines the format of the input and output. The format string always starts with a '%' character

The commonly used format specifiers in printf() function are:

Format Specifier Type
%c Character
%d Signed integer
%e or %E Scientific notation of floats
%f Float values
%g or %G Similar as %e or %E
%hi Signed integer (short)
%hu Unsigned integer (short)
%i Unsigned integer
%l or %ld or %li Long
%lf Double
%Lf Long double
%lu Unsigned int or unsigned long
%lli or %lld Long long
%llu Unsigned long long
%o Octal representation
%p Pointer
%s String
%u Unsigned int
%x or %X Hexadecimal representation

Let's understand the format specifiers in detail through an example.

%u: Unsigned Integer

                
#include <stdio.h>
int main()
{
int b = 10;
int c = -10;
printf("Value of b is: %u\n", b);
printf("nValue of c is: %u\n", c);
return 0;
}

Output

Value of b is: 10
Value of c is: 4294967286 (representation of -10 in unsigned format)

%o: Octal Format

                
#include <stdio.h>
int main()
{
int a = 0100; // Octal value
printf("Octal value of a is: %o\n", a);
printf("nInteger value of a is: %d\n", a);
return 0;
}

Output

Octal value of a is: 100
Integer value of a is: 64

%x and %X: Hexadecimal Format

                
#include <stdio.h>
int main()
{
int y = 0xA; // Hexadecimal value
printf("Hexadecimal value of y is: %x\n", y);
printf("nHexadecimal value of y is: %X\n", y);
printf("nInteger value of y is: %d\n", y);
return 0;
}

Output

Hexadecimal value of y is: a
Hexadecimal value of y is: A
Integer value of y is: 10

%f: Floating Point

                
#include <stdio.h>
int main()
{
    float y;
    printf("Enter a floating point value: ");
    scanf("%f", &y);
    printf("Floating point value of y is: %f\n", y);
    return 0;
}

Output

Enter a floating point value: 5.6 Floating point value of y is: 5.600000

%e and %E: Exponential Format

                
#include <stdio.h>
int main()
{
float y = 3;
printf("Exponential value of y is: %e\n", y);
printf("nExponential value of y is: %E\n", y);
return 0;
}

Output

Exponential value of y is: 3.000000e+00
Exponential value of y is: 3.000000E+00

%g: General Floating Point

                
#include <stdio.h>
int main()
{
float y = 3.8;
printf("Float value of y is: %g\n", y);
return 0;
}

Output

Float value of y is: 3.8

%p: Pointer (Address in Hexadecimal)

                                                
#include <stdio.h>
int main()
{
int y = 5;
printf("Address value of y in hexadecimal form is: %p\n", &y);
return 0;
}

Output

Address value of y in hexadecimal form is: 0x7ffeeafb1a0c (example address)

Minimum Field Width

                
#include <stdio.h>
int main()
{
    int x;
        
    // Prompting user for input
    printf("Enter an integer value: ");
    scanf("%d", &x);
        
    // Printing with 8 spaces, right-aligned
    printf("%8d\n", x);
        
    // Printing with 8 spaces, left-aligned
    printf("%-8d\n", x);
        
    return 0;
}

Output

Enter an integer value: 800 800 800

Specifying Precision

                
#include <stdio.h>
int main()
{
float x = 12.2;
printf("%.2f", x);
return 0;
}

Output

12.20