Less Used Format Specifiers in C

Some format specifiers are not used in every beginner program, but they are important for exams, number systems, memory concepts and larger integer values.

First study the common page: Format Specifiers in C.

Less Used Format Specifiers Table

Format Specifier Used For Data Type / Use Example
%u Unsigned integer unsigned int unsigned int x = 50;
%ld Long integer long int long int n = 100000;
%lld Long long integer long long int long long int n = 9000000000;
%hd Short integer short int short int x = 10;
%x Hexadecimal in lowercase int 255 prints ff
%X Hexadecimal in uppercase int 255 prints FF
%o Octal number int 8 prints 10
%e or %E Scientific notation float, double 1234.5 prints like 1.234500e+003
%p Address or pointer value Pointer printf("%p", &x);
%zu Result of sizeof size_t printf("%zu", sizeof(int));

1. %u - Unsigned Integer

%u is used for unsigned int. Unsigned integers store only zero and positive values.

#include <stdio.h>

int main() {
    unsigned int count = 50;
    printf("Count = %u", count);
    return 0;
}

Output:

Count = 50

Explanation:

  • count is an unsigned integer.
  • %u prints unsigned integer values.

2. %ld, %lld and %hd - Size Based Integer Specifiers

These specifiers are used when integer values are stored using short, long or long long. 

#include <stdio.h>

int main() {
    short int small = 10;
    long int population = 1000000;
    long long int distance = 9000000000;

    printf("Small = %hd\n", small);
    printf("Population = %ld\n", population);
    printf("Distance = %lld", distance);
    return 0;
}

Output:

Small = 10

Population = 1000000

Distance = 9000000000

Explanation:

  • %hd prints short integer.
  • %ld prints long integer.
  • %lld prints long long integer.

3. %x, %X and %o - Number System Specifiers

These specifiers print integer values in hexadecimal and octal number systems.

#include <stdio.h>

int main() {
    int number = 255;

    printf("Hex lowercase = %x\n", number);
    printf("Hex uppercase = %X\n", number);
    printf("Octal = %o", number);
    return 0;
}

Output:

Hex lowercase = ff

Hex uppercase = FF

Octal = 377

Explanation:

  • %x prints hexadecimal value in lowercase.
  • %X prints hexadecimal value in uppercase.
  • %o prints octal value.

4. %e and %E - Scientific Notation

%e and %E print decimal values in scientific notation. This is useful for very large or very small numbers.

#include <stdio.h>

int main() {
    double value = 12345.678;

    printf("Scientific = %e\n", value);
    printf("Scientific = %E", value);
    return 0;
}

Output:

Scientific = 1.234568e+004

Scientific = 1.234568E+004

Explanation:

  • %e prints scientific notation with lowercase e.
  • %E prints scientific notation with uppercase E.

6. %zu - sizeof Result Specifier

%zu is used to print values of type size_t. The sizeof operator returns a size_t value. 

#include <stdio.h>

int main() {
    printf("Size of int = %zu bytes", sizeof(int));
    return 0;
}

Possible Output:

Size of int = 4 bytes

Explanation:

  • sizeof(int) returns the memory size of int in bytes.
  • %zu is the correct specifier for printing sizeof result.

6. %zu - sizeof Result Specifier

%zu is used to print values of type size_t. The sizeof operator returns a size_t value. 

#include <stdio.h>

int main() {
    printf("Size of int = %zu bytes", sizeof(int));
    return 0;
}

Possible Output:

Size of int = 4 bytes

Explanation:

  • sizeof(int) returns the memory size of int in bytes.
  • %zu is the correct specifier for printing sizeof result.

Combined Example of Less Used Format Specifiers

#include <stdio.h>

int main() {
    unsigned int rank = 5;
    long int population = 1000000;
    int number = 255;

    printf("Rank = %u\n", rank);
    printf("Population = %ld\n", population);
    printf("Hex = %X\n", number);
    printf("Octal = %o\n", number);
    printf("Size of int = %zu bytes", sizeof(int));

    return 0;
}

Possible Output:

Rank = 5

Population = 1000000

Hex = FF

Octal = 377

Size of int = 4 bytes

Explanation:

  • %u prints unsigned integer.
  • %ld prints long integer.
  • %X prints hexadecimal in uppercase.
  • %o prints octal value.
  • %zu prints sizeof result.

Summary:

  • Less used format specifiers are important for special cases.
  • %u is used for unsigned integer.
  • %ld, %lld and %hd are used for different integer sizes.
  • %x, %X and %o are used for number systems.
  • %p is used for addresses and %zu is used for sizeof result.

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