21 Nov C Structures
Let us understand Structures in C programming. In this lesson, we will cover the following concepts related to structures:
- What are Structures
- Define a Structure
- Declare a Structure in two ways
- Access Structure Members
- Example of Structures covering the above concepts
What are Structures
Structures in C allow you to store data of different types. Easily store variables of types, such as int, float, char, etc. For example, storing the details of employees, with the following members:
- name: string type
- age: int type
- zone: string type
- salary: float type
You might wonder about the difference between structures and arrays. Well, Arrays store data of similar types, such as an array of ints, whereas Structures store data of different types.
Define a Structure
Let us understand the above concept with an example to define a structure. To define a structure, use the struct keyword:
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struct emp { char name[15]; int age; char zone[10]; float salary; }; |
Above,
- The name of the structure is emp,
- The structure members or fields are name, age, zone, and
Declare a Structure
We defined the structure above. Let us now see how to declare a structure using two ways:
- Declare a structure while defining it.
- Declare a structure with struct
1. Declare a structure while defining it
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struct emp { char name[15]; int age; char zone[10]; float salary; }; e1, e2, e3; |
The e1, e2, and e3 above are variables. We can use them to access the values.
2. Declare a structure with struct
We can also declare the variables e1, e2, e3 using the struct keyword. First, define it:
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struct emp { char name[15]; int age; char zone[10]; float salary; }; |
Declare e1, e2, and e3 of type emp:
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struct emp e1, e2, e3; |
Access Structure Members
To access a structure member in C language, use a period i.e. the member access operator. Following is the syntax:
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structure_variable.structure_member |
For example, access the structure members for variable e1 i.e. the 1st employee:
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e1.name e1.age e1.zone e1.salary |
C Structures – Example
Let us see an example of creating a structure in C. We will define and declare a structure, and also learn to access structure members in C:
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#include <stdio.h> #include <string.h> struct Emp { char name[15]; int age; char zone[10]; float salary; }; int main( ) { // Declare e1, e2, e3 of type Emp struct Emp e1; struct Emp e2; struct Emp e3; // Set the Employee1 information strcpy(e1.name, "John"); e1.age = 25; strcpy(e1.zone, "North"); e1.salary=30000; // Display Employee1 data printf("Employee1 1 name = %s\n", e1.name); printf("Employee1 1 age = %d\n", e1.age); printf("Employee1 1 zone = %s\n", e1.zone); printf("Employee1 1 salary = %f\n", e1.salary); return 0; } |
Output
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Employee1 1 name = John Employee1 1 age = 25 Employee1 1 zone = North Employee1 1 salary = 30000.000000 |
In the above example, we have used strcpy. In C, strings can’t be directly assigned using the = operator because arrays, including character arrays, don’t support direct assignment. Therefore, strcpy was used to copy the contents of one string to another.
Structures example without strcpy
Let us see another example without using strcpy. For that, initialize the structure at the time of declaration:
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struct Emp e1 = {"David", 30, "East", 40000.5}; |
Here is the same example without using strcpy:
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// Structures example in C #include<stdio.h> struct Emp { char name[15]; int age; char zone[10]; float salary; }; int main() { struct Emp e1 = {"David", 30, "East", 40000.5}; // Display Employee1 data printf("Employee Name = %s\n", e1.name); printf("Employee Age = %d\n", e1.age); printf("Employee Zone = %s\n", e1.zone); printf("Employee Salary = %.2f\n", e1.salary); return 0; } |
Output
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Employee Name = David Employee Age = 30 Employee Zone = East Employee Salary = 40000.50 |
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