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Array of structs

Learn to create an array of structs and iterate it.

Array of structs

You can declare an array of a struct type. This is ideal to manage multiple records under one structure.

struct Point points[3] = {
    {1, 2},
    {3, 4},
    {5, 6}
};

Here points holds three struct Point. Each element carries its own x and y. You access the first point's x with points[0].x. You can loop over all points.

Looping over a struct array

You can iterate over a struct array with a for loop. For each element, member access uses the [i].member form.

for (int i = 0; i < 3; i++) {
    printf("%d %d\n",
        points[i].x,
        points[i].y);
}

Here i goes from 0 to 3; each step prints one point's coordinates. The chain points[i].x first takes the i-th element, then reaches its x member. This pattern is standard to process data tables.

Practice Print three points

Define struct Point (int x, int y). In main create a three-point array: {{1, 2}, {3, 4}, {5, 6}}. Use a for loop to print each point with printf.

Starter code

main.c
#include <stdio.h>

struct Point { int x; int y; };

int main(void) {
    /* Declare an array of three Points; loop with for; print with printf */
    return 0;
}

Sample solution

main.c
struct Point points[3] = {{1, 2}, {3, 4}, {5, 6}};
for (int i = 0; i < 3; i++) {
    printf("%d %d\n", points[i].x, points[i].y);
}

Expected output

1 2
3 4
5 6

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What does points[1].x represent?

  • The x member of the 2nd element
  • The x member of the first element Correct answer
  • A Point pointer
  • All x members of the array

Explanation: points[1] is the second element; .x is its x member.

2 Match expression to meaning

Term Meaning
points[0] First element
points[2] Third element
points[i].x x of i-th element
points[3] Out of bounds

3 Fill in the blank: array element access

Question 
printf("%d
", points____);
Answer 
printf("%d
", points[0].x);

Explanation: points[0].x gives the first element's x member.

All lessons in Beginner

1 C basics

  1. What is C?
  2. Your first program
  3. Compile and run
  4. Comments
  5. printf and escapes
  6. Summary - C basics

2 Variables

  1. Declaring variables
  2. Variable assignment
  3. const
  4. Variable scope
  5. typedef
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. char
  4. sizeof
  5. Type conversion
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Menu loop
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Bitwise operators
  6. Summary - Operators

6 I/O

  1. printf formatting
  2. scanf
  3. Multiple inputs
  4. getchar and putchar
  5. puts and fputs
  6. Summary - I/O

7 Conditionals

  1. The if statement
  2. else and else if
  3. The switch statement
  4. The ternary operator
  5. Nested conditionals
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. break and continue
  5. Nested loops
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding products
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Array size
  4. Multidimensional arrays
  5. Arrays and loops
  6. Summary - Arrays

11 Strings

  1. String basics
  2. String literals
  3. strlen
  4. strcpy and strcat
  5. strcmp
  6. Summary - Strings

12 Functions

  1. Defining functions
  2. Return values
  3. Parameters
  4. Function prototypes
  5. Recursion
  6. Summary - Functions

13 Pointer basics

  1. What is a pointer?
  2. The & address operator
  3. Pointer dereference
  4. NULL
  5. Pointer arithmetic
  6. Summary - Pointer basics

14 Arrays and pointers

  1. Array name as pointer
  2. Pointer to array
  3. Passing arrays to functions
  4. Pointer loop
  5. Multidim array pointer
  6. Summary - Arrays and pointers

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 String functions

  1. strchr
  2. strstr
  3. strtok
  4. sprintf
  5. sscanf
  6. Summary - String functions

17 Structs

  1. Defining structs
  2. Using structs
  3. typedef struct
  4. Array of structs
  5. Nested structs
  6. Summary - Structs

18 Memory and stack

  1. Stack and heap
  2. Automatic storage
  3. malloc
  4. free
  5. calloc and realloc
  6. Summary - Memory and stack

19 Preprocessor

  1. #define
  2. #include
  3. Conditional compilation
  4. Macro functions
  5. Header files
  6. Summary - Preprocessor

20 Beginner final

  1. Project design
  2. Data model
  3. Functions
  4. Memory management
  5. Putting it together