C - Structure

Besides the primitive data types like int, char, float etc, C language provides us another data type called structure. By using, structure, C allow us to create a data type, which can be a collection of different primitive data type elements. To understand structure, let's take an example.

Let's suppose, we have to store a collection of information about a bag, such as -

The gender type of a bag in char data type.
The price of a bag in float data type.
The year of manufacturing of a bag in int data type.

Using structure we can create a data type which can be used a collection of different data types mentioned above. To understand structure, let's see how a structure is declared.

Declaring the structure

struct <name_of_structure>
{
1st element of structure;
2nd element of structure;
3rd element of structure;
...
};

We can declare a structure using the struct keyword, followed by any name of structure of our choice.
Next, we have an opening brace { after which we can declare any number of structure elements, where each element ends with a semicolon ;
Next, after declaring all the elements, the declaration of structure ends with a closing brace }, followed by a semicolon ;

Declaring a variable of structure type

one or multiple

struct

name of the structure

name of variables

multiple names are separated by a comma

struct <name_of_structure> <name_of_variables>;

Understanding structure by an example

bag

A char variable named gender_type.
A int variable named year_of_make.
A float variable named price.

/* An example of structure */


#include<stdio.h>

int main()
{

/* Declaring a structure */
struct bag
{
	char gender_type;
	int year_of_make;
	float price;
};

/* Declaring a structure variable */
struct bag b1;

printf("Enter the  gender type of the bag : ");
scanf("%c", &b1.gender_type);

printf("Enter the year of make of the bag :");
scanf("%d", &b1.year_of_make);

printf("Enter the price of the bag : ");
scanf("%f", &b1.price);


printf("The gender type of the bag : %c", b1.gender_type);
printf("\n");

printf("The year of make of the bag : %d", b1.year_of_make);
printf("\n");

printf("The price of the bag :  : %.2f", b1.price);

return 0;
}

Output is :

Enter the  gender type of the bag : M
Enter the year of make of the bag :2018
Enter the price of the bag : 99.9
The gender type of the bag : M
The year of make of the bag : 2018
The price of the bag :  : 99.90

Program Analysis

In this code above, we have created a structure named bag. This structure can also be termed as a user-defined data type which can be used to create variables of its type.

struct bag
{
char gender_type;
int year_of_make;
float price;
};

We have created a variable named b1 of structure type by using the struct keyword with the name of the structure, such as -
```
 struct bag b1; 
```

Next, we have individually initialized the elements of structure with values by using them with dot-operator in scanf() function. For example -
```
printf("Enter the  gender type of the bag : ");
scanf("%c", &b1.gender_type);
```

Finally, we have displayed the initialized values in the elements of structure(one-by-one) by using the dot-operator in printf() function. For example -
```
printf("The price of the bag :  : %.2f", b1.price);
```