A struct (or structure) is a mixed data type in C. You can use it to store variables in different types.
The struct type is comparable to classes in object-oriented programming. Sometimes you may need to assign values to objects with the same properties. Instead of creating multiple variables for these objects in your C program, you can define them in a struct.
Creating a Struct
To define a structure, use the keyword struct, followed by the structure name. Inside the structure, you can specify variables of different types:
struct Car{
char name[45];
int wheels;
double cost;
} ;You can define several instances of Car by adding those instance declarations after the right brace in your struct declaration:
struct Car{
/* variables */
} Car1, Car2, Car3;You can also nest a structure inside a structure. See the example below:
struct address {
int area_code;
char street_name[45];
};
struct Person {
char name[60];
float height;
struct address Persons_location;
};
Operations on Struct Types
Initialization
There are three ways in which you can initialize the elements of a struct.
You can insert the comma-separated values in {} brackets & then assign them to the structure. You should note that the values must be in the same order that you declared the variables.
struct Car Car1 = {"Truck", 10, 65000};
You can also assign the values without minding the order in which you declared them. See the example below.
struct Car Car2 = {
.cost = 45000,
.name = "Truck",
.wheels = 8
};The third way to initialize your struct is to assign it an existing structure of the same type.
struct Car Car3 = Car1;Accessing Struct Elements
To access the value stored in a structure element, use the dot operator.
/* the syntax is:
structName.elementName */
int y = Car1.wheels;A Look at Object-Oriented Programming
As mentioned at the beginning, struct is comparable to using classes in object-oriented programming (OOP). Classes are simpler to use and enable code reuse.
For this reason and many others, C++ was introduced. C++ is the object-oriented version of C. Next on your reading list should be understanding the concepts in OOP.