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Defining Structures
A structure is defined using the ‘struct‘ keyword followed by the structure name and a block containing the structure members.
Syntax
struct StructureName {
dataType member1;
dataType member2;
// more members
};
Example
struct Person {
char name[50];
int age;
float height;
};
In this example, ‘struct Person‘ is a structure with three members: ‘name‘ (a character array), ‘age‘ (an integer), and ‘height‘ (a floating-point number).
Declaring Structure Variables
Once a structure is defined, you can declare variables of that structure type. There are multiple ways to declare structure variables:
1. Separately from Definition:
struct Person person1, person2;
2. Combined with Definition:
struct Person {
char name[50];
int age;
float height;
} person1, person2;
3. Using typedef:
The ‘typedef‘ keyword can be used to create an alias for the structure type, making it easier to declare variables.
typedef struct {
char name[50];
int age;
float height;
} Person;
Person person1, person2;
Accessing Structure Members
Structure members are accessed using the dot (‘.‘) operator for direct access or the arrow (‘->‘) operator when using pointers.
Using the Dot Operator
person1.age = 30;
strcpy(person1.name, "Alice");
person1.height = 5.5;
Using the Arrow Operator
When dealing with pointers to structures, the arrow operator (‘->‘) is used to access members.
Person *ptr = &person1;
ptr->age = 30;
strcpy(ptr->name, "Alice");
ptr->height = 5.5;
Initializing Structures
Structures can be initialized at the time of declaration.
Person person1 = {"Alice", 30, 5.5};
Nested Structures
Structures can contain other structures as members.
struct Date {
int day;
int month;
int year;
};
struct Person {
char name[50];
struct Date birthdate;
};
struct Person person1 = {"Alice", {15, 6, 1990}};
Example Program
Here is a complete example that demonstrates defining, declaring, initializing, and accessing structure members.
#include <stdio.h>
#include <string.h>
// Define the structure
struct Person {
char name[50];
int age;
float height;
};
int main() {
// Declare and initialize structure variables
struct Person person1 = {"Alice", 30, 5.5};
struct Person person2;
// Access and modify structure members
strcpy(person2.name, "Bob");
person2.age = 25;
person2.height = 6.0;
// Print structure members
printf("Person 1: %s, %d years old, %.1f feet tall\n", person1.name, person1.age, person1.height);
printf("Person 2: %s, %d years old, %.1f feet tall\n", person2.name, person2.age, person2.height);
return 0;
}
Key Points to Remember
- Definition: Use the
structkeyword followed by structure name and member definitions. - Declaration: Declare structure variables separately or along with the definition.
- Access: Use the dot operator for direct access and the arrow operator for pointers.
- Initialization: Structures can be initialized at the time of declaration.
- Nested Structures: Structures can include other structures as members for complex data modeling.
Understanding structures is fundamental to handling complex data types in C, enabling more organized and readable code.
