8. C Datatypes

In the C programming language, data types refer to a domain of allowed values & the operations that can be performed on those values. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted. There are 4 fundamental (primitive) C datatypes, which are- char, int, float &, double. Char is used to store any single character; int is used to store any integer value, float is used to store any single precision floating point number & double is used to store any double precision floating point number.
You can use two qualifiers to expand the range of these basic types.

• a. Sign qualifier– signed & unsigned
• b. Size qualifier- short & long

Why to Use of Data Types?

• To identify the type of a variable when it declared.
• To identify the type of the return value of a function.
• To identify the type of a parameter expected by a function.

ANSI C provides three types of data types:

• Primary(Built-in) Data Types:
  void, int, char, double and float.
• Derived Data Types:
  Array, References, and Pointers.
• User Defined Data Types:
  Structure, Union, and Enumeration.

Classification Chart

Primitive Datatypes

Declaration of Primary Data Types with Variable Names

After taking suitable variable names, they need to be assigned with a data type. This is how the data types are used along with variables:

Examples of Primitive datatypes

Example 1:

int    age;
char   letter;
float  height, width;
char answer, choice;

Example 2:

#include <stdio.h>
int main()
{
    int a = 4000; // positive integer data type
    float b = 5.2324; // float data type
    char c = 'Z'; // char data type
    long d = 41657; // long positive integer data type
    long e = -21556; // long -ve integer data type
    int f = -185; // -ve integer data type
    short g = 130; // short +ve integer data type
    short h = -130; // short -ve integer data type
    double i = 4.1234567890; // double float data type
    float j = -3.55; // float data type
}

Difference between Float and Double Data Types

Derived Data Types

C language supports three derived datatypes

User Defined Data Types

C datatypes allows the feature called type definition which allows programmers to define their identifier that would represent an existing data type.

Write a program to check a datatype size.

The storage representation and machine instructions vary from one machine to another. The sizeof operator can be used to obtain the precise size of a type or variable on a specific platform. On some platforms, the size of a type or variable may be different due to factors such as the underlying architecture, compiler, and operating system. It is important to consider these differences when writing code that needs to be portable across different machines.

// Program to check the datatype or its variable size 
// use keyword sizeof to find a size.
#include <stdio.h>
#include <float.h>
int main() {
   printf("Storage size for void : %d \n", sizeof(void));
   printf("Storage size for char : %d \n", sizeof(char));
   printf("Storage size for float : %d \n", sizeof(float));
   printf("Storage size for double : %d \n", sizeof(double));
   printf("Storage size for int : %d \n", sizeof(int));
   printf("Storage size for long int : %d \n", sizeof(long int));
   printf("Storage size for unsigned int : %d \n", sizeof(unsigned int));
   printf("Storage size for unsigned long int : %d \n", sizeof(unsigned long int));
   printf("Storage size for long double : %d \n", sizeof(long double));
   printf("Minimum long double  negative value: %E\n", LDBL_MIN );
   printf("Maximum long double  positive value: %E\n", LDBL_MAX );
   printf("Precision value: %d\n", LDBL_DIG );
    
   return 0;
}

Output