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	Description
%d or %i	It is used to print the signed integer value where signed integer means that the variable can hold both positive and negative values.
%u	It is used to print the unsigned integer value where the unsigned integer means that the variable can hold only positive value.
%o	It is used to print the octal unsigned integer where octal integer value always starts with a 0 value.
%x	It is used to print the hexadecimal unsigned integer where the hexadecimal integer value always starts with a 0x value. In this, alphabetical characters are printed in small letters such as a, b, c, etc.
%X	It is used to print the hexadecimal unsigned integer, but %X prints the alphabetical characters in uppercase such as A, B, C, etc.
%f	It is used for printing the decimal floating-point values. By default, it prints the 6 values after '.'.
%e/%E	It is used for scientific notation. It is also known as Mantissa or Exponent.
%g	It is used to print the decimal floating-point values, and it uses the fixed precision, i.e., the value after the decimal in input would be exactly the same as the value in the output.
%p	It is used to print the address in a hexadecimal form.
%c	It is used to print the unsigned character.
%s	It is used to print the strings.
%ld	It is used to print the long-signed integer value.

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

• %d

1. int main()  
2. {  
3.   int b=6;  
4.   int c=8;  
5.   printf("Value of b is:%d", b);  
6.   printf("\nValue of c is:%d",c);  
7.   
8.     return 0;  
9. }  

In the above code, we are printing the integer value of b and c by using the %d specifier.

 

 

 

 

 

Output

• %u

1. int main()  
2. {  
3.   int b=10;  
4.   int c= -10;  
5.   printf("Value of b is:%u", b);  
6.   printf("\nValue of c is:%u",c);  
7.   
8.     return 0;  
9. }  

In the above program, we are displaying the value of b and c by using an unsigned format specifier, i.e., %u. The value of b is positive, so %u specifier prints the exact value of b, but it does not print the value of c as c contains the negative value.

Output

• %o

1. int main()  
2. {  
3.   int a=0100;  
4.   printf("Octal value of a is: %o", a);  
5.   printf("\nInteger value of a is: %d",a);  
6.   return 0;  
7. }  

In the above code, we are displaying the octal value and integer value of a.

Output

• %x and %X

1. int main()  
2. {  
3.   int y=0xA;  
4.   printf("Hexadecimal value of y is: %x", y);  
5.   printf("\nHexadecimal value of y is: %X",y);  
6.   printf("\nInteger value of y is: %d",y);  
7.     return 0;  
8. }  

In the above code, y contains the hexadecimal value 'A'. We display the hexadecimal value of y in two formats. We use %x and %X to print the hexadecimal value where %x displays the value in small letters, i.e., 'a' and %X displays the value in a capital letter, i.e., 'A'.

Output

• %f

1. int main()  
2. {  
3.   float y=3.4;  
4.   printf("Floating point value of y is: %f", y);  
5.   return 0;  
6. }  

The above code prints the floating value of y.

Output

• %e

1. int main()  
2. {  
3.   float y=3;  
4.   printf("Exponential value of y is: %e", y);  
5.   return 0;  
6. }  

Output

• %E

1. int main()  
2. {  
3.   float y=3;  
4.   printf("Exponential value of y is: %E", y);  
5.   return 0;  
6. }  

Output

• %g

1. int main()  
2. {  
3.   float y=3.8;  
4.   printf("Float value of y is: %g", y);  
5.   return 0;  
6. }  

In the above code, we are displaying the floating value of y by using %g specifier. The %g specifier displays the output same as the input with a same precision.

Output 

• %p

1. int main()  
2. {  
3.   int y=5;  
4.   printf("Address value of y in hexadecimal form is: %p", &y);  
5.   return 0;  
6. }  

Output

• %c

1. int main()  
2. {  
3.   char a='c';  
4.   printf("Value of a is: %c", a);  
5.   return 0;  
6. }  

Output

• %s

1. int main()  
2. {  
3.   printf("%s", "javaTpoint");  
4.   return 0;  
5. }  

 

Output

Minimum Field Width Specifier

Suppose we want to display an output that occupies a minimum number of spaces on the screen. You can achieve this by displaying an integer number after the percent sign of the format specifier.

1. int main()  
2. {  
3.  int x=900;  
4.   printf("%8d", x);  
5.   printf("\n%-8d",x);  
6.   return 0;  
7. }  

• %p

1. int main()  
2. {  
3.   int y=5;  
4.   printf("Address value of y in hexadecimal form is: %p", &y);  
5.   return 0;  
6. }  

Output

• %c

1. int main()  
2. {  
3.   char a='c';  
4.   printf("Value of a is: %c", a);  
5.   return 0;  
6. }  

Output

• %s

1. int main()  
2. {  
3.   printf("%s", "javaTpoint");  
4.   return 0;  
5. }  

Output

Minimum Field Width Specifier

Suppose we want to display an output that occupies a minimum number of spaces on the screen. You can achieve this by displaying an integer number after the percent sign of the format specifier.

1. int main()  
2. {  
3.  int x=900;  
4.   printf("%8d", x);  
5.   printf("\n%-8d",x);  
6.   return 0;  
7. }