Data Types in C
In C programming, data types specify how the data is to be stored and manipulated.
The basic C data types are:
-
int:
intis used to store integer values (whole numbers). It typically occupies 4 byte of memory. -
float:
floatis used to store floating-point numbers (numbers with decimal points), typically providing 6 decimal digits of precision. It typically occupies 4 byte of memory. -
double:
doubleis used to store floating-point numbers with double precision, typically providing 15 decimal digits of precision. It typically occupies 8 byte of memory. -
char:
charis used to store single characters (like letters, digits, symbols). It typically occupies 1 byte of memory. -
_Bool:
_Boolis used for 'True' or 'False' (0 or 1). 0 represents false and non-zero represents true.
Derived data types are:
- Arrays: An array is a collection of items of the same data type stored under a single name.
- Pointers: Pointers store memory addresses of variables. They are used for advanced memory management.
- Structures: Structures allow you to group variables of different data types under a single name, creating user-defined data types.
- Unions: Unions are similar to structures, but all members share the same memory location. This is useful when you know only one member will have a value at a time.
Other data types:
-
void:
voidindicates the absence of a value. It's often used for functions that don't return any value.
Create Integer Data Type in C
To define an integer data type, use int keyword before variable name.
Examples of Integer Data Type
Example explained
-
int num;: The code declares an integer variable named 'num'. -
num = 100;: It assigns the integer value 100 to the variable 'num'. -
printf("%d", num);: It prints the value of integer variable named 'num'. '%d' is the format specifier for integer.
Create Float Data Type in C
To define a float data type, use float keyword before variable name.
Examples of Float Data Type
Example explained
-
float numFloat;: The code declares a float variable named 'numFloat'. -
numFloat = 32.54;: It assigns the float value 32.54 to the variable 'numFloat'. -
printf("%f", numFloat);: It prints the value of float variable named 'numFloat'. '%f' is the format specifier for float.
Create Double Data Type in C
To define a double data type, use double keyword before variable name.
Examples of Double Data Type
Example explained
-
double numDouble;: The code declares a double variable named 'numDouble'. -
numDouble = 564.25647;: It assigns the double value 564.25647 to the variable 'numDouble'. -
printf("%lf", numDouble);: It prints the value of double variable named 'numDouble'. '%lf' is the format specifier for double.
Create Char Data Type in C
To define a char data type, use char keyword before variable name.
Examples of Char Data Type
Example explained
-
char letter;: The code declares a char variable named 'letter'. -
letter = 'A';: It assigns the char value 'A' to the variable 'letter'. -
printf("%c", letter);: It prints the value of char variable named 'letter'. '%c' is the format specifier for char.
Create Boolean Data Type in C
To define a boolean data type, use bool keyword before variable name.
You must include stdbool.h header to use bool.
Examples of Boolean Data Type
Example explained
-
bool isTrue;: The code declares a boolean variable named 'isTrue'. -
isTrue = true;: It assigns the boolean value 'true' to the variable 'isTrue'. -
printf("isTrue: %s\n", (isTrue) ? "true" : "false"):It prints the value of boolean variable named 'isTrue'. The ternary operator method is used for better readability.
Create Array in C
To declare an array, specify the data type of the elements before the array name. The array name must be followed by square brackets []. The size of the array is put in the square brackets in integer value greater than zero.
Array elements are placed between curly braces '{}' and are separated by comma.
You can initialize the array with elements at the time of declaration or you can add elements later.
Examples of Array
Example explained
-
int numbers[5] = {1, 2, 3, 4, 5};: The code declares and initializes an integer array of 5 numbers. -
printf("%d\n", numbers[2]);: It prints the third element of integer array. Index of C array is 0 (zero) based.
Create Pointer in C
- Specify the data type of the pointer.
- Use the * operator to declare a pointer variable name. The * operator is conventionally placed at the beginning of the variable name to indicate that it's a pointer.
- Use the address-of operator '&' before a variable to get the memory address of the variable, and assign it to the pointer variable.
Examples of Pointer
Example explained
-
int num = 20;: The code declares and initializes an integer variable 'num'. -
int *numptr = #: It declares a pointer name '*numptr' and assigns the memory address of 'num' variable using '&num'. Please note that '&' operator is used with 'num' varibale to get the memory address of the variable. -
printf("The memory address of num: %p\n", numptr);: It prints the memory address of 'num' variable using pointer 'numptr'. '%p' is the format specifier for pointer.
Create Structure in C
-
Use 'struct' keyward before structure name like
struct Person. Person is the user defined name of structure. -
Define members of the structure inside curly braces '{}' like
{ char name[60]; int age; };. Declare data type before the member name to define a struct member.
Please take a closer look at the following example.
Examples of Pointer
Example explained
-
struct Person { char name[60]; int age;};: The line declares Person structure with two members - 'name' and 'age'. -
struct Person person1;: It declares a variable of type 'Person' structure name 'person1'. -
strcpy(person1.name, "John Done");: The line copies string value ("John Done") to the name member. -
person1.age = 35;: It assigns '35' to the 'age' member of Person structure. -
printf( "%s is %d years old.", person1.name, person1.age);: It prints the member values of Person structure.
