C Data Types

Primary Data Types

C provides several built-in data types. The size of each type may vary by platform, but the values below are typical for a 64-bit system.

Type	Size	Format Specifier	Range	Description
`int`	4 bytes	`%d` or `%i`	-2,147,483,648 to 2,147,483,647	Integer numbers
`float`	4 bytes	`%f`	~3.4Ã—10â»³â¸ to 3.4Ã—10³â¸	Single-precision decimal
`double`	8 bytes	`%lf`	~1.7Ã—10â»³â°â¸ to 1.7Ã—10³â°â¸	Double-precision decimal
`char`	1 byte	`%c`	-128 to 127 (or 0 to 255)	Single character
`void`	—	—	—	No value (used for functions/pointers)

Type Modifiers

Type modifiers change the size or sign of a base type. They can be combined with int, char, and double.

Type	Size	Format Specifier	Range
`short int`	2 bytes	`%hd`	-32,768 to 32,767
`unsigned int`	4 bytes	`%u`	0 to 4,294,967,295
`long int`	4 or 8 bytes	`%ld`	-2,147,483,648 to 2,147,483,647 (min)
`long long int`	8 bytes	`%lld`	-9.2Ã—10Â¹â¸ to 9.2Ã—10Â¹â¸
`unsigned long long`	8 bytes	`%llu`	0 to 1.8Ã—10Â¹â¹
`unsigned char`	1 byte	`%c`	0 to 255
`long double`	10 or 16 bytes	`%Lf`	Extended precision

Derived Types

C also has derived data types that are built from primary types:

Arrays — collection of elements of the same type
Pointers — variables that store memory addresses
Structures — group of variables of different types under one name
Unions — similar to structures but share the same memory
Functions — blocks of reusable code

Declaring and Printing All Data Types

#include <stdio.h>

int main() {
    int    age    = 25;
    float  price  = 9.99f;
    double pi     = 3.14159265358979;
    char   grade  = 'A';

    printf("int:    %d\n",  age);
    printf("float:  %f\n",  price);
    printf("double: %lf\n", pi);
    printf("char:   %c\n",  grade);

    // Printing char as integer (ASCII value)
    printf("char as int: %d\n", grade);  // 65

    return 0;
}

/*
Output:
int:    25
float:  9.990000
double: 3.141593
char:   A
char as int: 65
*/

sizeof Operator and Type Modifiers

#include <stdio.h>

int main() {
    // sizeof returns the size in bytes
    printf("Size of char:           %zu bytes\n", sizeof(char));
    printf("Size of int:            %zu bytes\n", sizeof(int));
    printf("Size of float:          %zu bytes\n", sizeof(float));
    printf("Size of double:         %zu bytes\n", sizeof(double));
    printf("Size of long int:       %zu bytes\n", sizeof(long int));
    printf("Size of long long int:  %zu bytes\n", sizeof(long long int));
    printf("Size of unsigned int:   %zu bytes\n", sizeof(unsigned int));

    // Type modifiers in action
    unsigned int  population = 4294967295U;  // max unsigned int
    long long int bigNum     = 9223372036854775807LL;
    short int     small      = 32767;

    printf("\nunsigned int:   %u\n",   population);
    printf("long long int:  %lld\n",  bigNum);
    printf("short int:      %hd\n",   small);

    return 0;
}

/*
Output (64-bit system):
Size of char:           1 bytes
Size of int:            4 bytes
Size of float:          4 bytes
Size of double:         8 bytes
Size of long int:       8 bytes
Size of long long int:  8 bytes
Size of unsigned int:   4 bytes
*/

Previous Next

C Data Types

Primary Data Types

Type Modifiers

Derived Types

Ready to Level Up Your Skills?