Variables & Data Types In C: C Tutorial #6

So guys in this tutorial, we are going to learn about variables and go over various data types. This tutorial is mostly going to be theoretical, and we will only touch the code for the purpose of understanding, except for that we will not be performing any coding related work, as theory is what makes your basis strong and a firm foundation can help you grasp the coding part more efficiently. 

As we have already discussed in the previous tutorial while going through identifiers that variables are nothing more than simple names given to a specific space in memory for reservation. I will get into more detail about it with the help of an example but first, let us cover some basics.

Declaration:

We cannot declare a variable without specifying its data type. The data type of a variable depends on what we want to store in the variable and how much space we want it to hold. The syntax for declaring a variable is simple:

data_type  variable_name;

or

data_type  variable_name = value;

the data type can be int, float, char, depending on what kind of value we want to store.

Naming a Variable:

A variable name can be of anything, we want to call out variable. Yet there are specific rules we must follow while naming a variable:

• A variable name can contain alphabets, digits, and underscore (-) only.
• The starting letter can not be a digit.
• White spaces cannot be used.
• The name should not be reserved keyword or special character.

We can declare and assign value to a variable in two ways.

1^st way:

int a = 12;

2^nd way:

int a;

a= 12;

Both of these have exactly the same working.

 A variable as its names define can be altered, or its value can be changed, but the same is not true for its type. If a variable is of integer type, then it will only store an integer value, which means that we cannot assign a character type value to an integer variable. We can not even store a decimal value into an integer variable.

Let’s see this with an example:

Example 1:

#include <stdio.h>

 

int main()

{

    int a = 12.2221;

    printf("Output = %d" , a);

    return 0;

}

We are sending 12.2221 as a value in a, but since it is an integer type variable, the output will be only 12.

Output = 12

 

Example 2:

#include <stdio.h>

 

int main()

{

    float a = 12.2221;

    printf("Output = %f" , a);

    return 0;

}

Here we are using float as a data type. In this case, you can see the output below is 12.222100

Output = 12.222100

Note that we used %f instead of %d in the case of float.

The reason is that int can store only 2 bytes worth of data as its storage capacity is 2 bytes while float storage capacity is 4 bytes.

 

DATA TYPE	MEMORY (BYTES)	RANGE
Char	1	-128 to 127
signed char	1	-128 to 127
unsigned char	1	0 to 255
short int	2	-32,768 to 32,767
unsigned short int	2	0 to 65,535
unsigned int	4	0 to 65,535
Int	2	--32,768 to 32,767
long int	4	-2,147,483,648 to 2,147,483,647
unsigned long int	4	0 to 4,294,967,  295
Float	4
Double	8
long double	10

Code as described

#include <stdio.h>

 

int main()

{

  

    printf("%lu",sizeof(int));

    return 0;

}