Array of Structures in C

An array of structures is an array where each element is a structure. It is one of the most common and powerful ways to store multiple records of the same type in C (like list of students, employees, books, products, etc.).

Think of it as a simple database table where each row is one structure and all rows have the same structure (same fields).

1. Declaring an Array of Structures

First define the structure, then create an array of that structure type.

              
            
C

            
            #include <stdio.h>
#include <string.h>

struct Student {
    char name[50];
    int roll;
    float marks;
};

int main() {
    // Method 1: Declare array
    struct Student class[5];          // array of 5 students
    
    // Method 2: With size and initialization
    struct Student top3[3] = {
        {"Rahul", 101, 92.5},
        {"Priya", 102, 95.8},
        {"Aman", 103, 88.4}
    };
    
    return 0;
}
          

2. Accessing Elements of Array of Structures

You can access members using two ways:

array[index].member
(array + index)->member (pointer style)

              
            
C

          Access and print array of structures
        
for(int i = 0; i < 3; i++) {
    printf("Student %d:\n", i+1);
    printf("Name : %s\n", top3[i].name);
    printf("Roll : %d\n", top3[i].roll);
    printf("Marks: %.1f\n\n", top3[i].marks);
}

// Using pointer notation (same result)
// printf("%s\n", (top3 + i)->name);

3. Taking Input for Array of Structures

              
            
C

          Reading data from user into array of structures
        
struct Student class[60];
int n;

printf("How many students? ");
scanf("%d", &n);

for(int i = 0; i < n; i++) {
    printf("\nEnter details of student %d:\n", i+1);
    printf("Name: ");
    scanf(" %49[^\n]", class[i].name);  // safe string input
    printf("Roll: ");
    scanf("%d", &class[i].roll);
    printf("Marks: ");
    scanf("%f", &class[i].marks);
}

4. Common Real-World Uses of Array of Structures

Use Case	Structure Name	Typical Size
Student management system	Student	30–200
Employee database	Employee	500–5000
Book inventory	Book	1000+
Product catalog	Product	200–10000
Contact list / Phone book	Contact	100–1000
Transaction history	Transaction	1000+

5. Passing Array of Structures to Function

You can pass array of structures to a function in two main ways:

Pass whole array (decays to pointer)
Pass individual structure (by value or pointer)

              
            
C

          Passing array of structures to function
        
void printStudents(struct Student s[], int size) {
    for(int i = 0; i < size; i++) {
        printf("%-20s %4d %6.1f\n",
               s[i].name, s[i].roll, s[i].marks);
    }
}

// Call in main:
// printStudents(top3, 3);