Array Traversal Patterns in DSA C

Mental Model

Go through each item in the list one by one to see or use it.

Analogy: Like reading a book from the first page to the last page, looking at every word in order.

[0] -> [1] -> [2] -> [3] -> [4] -> null
 ↑

Dry Run Walkthrough

Input: array: [10, 20, 30, 40, 50]

Goal: Visit each element in the array from start to end and print it

Step 1: Start at index 0, read value 10

[0:10↑] -> [1:20] -> [2:30] -> [3:40] -> [4:50] -> null

Why: We begin at the first element to start traversal

Step 2: Move to index 1, read value 20

[0:10] -> [1:20↑] -> [2:30] -> [3:40] -> [4:50] -> null

Why: Move to next element to continue traversal

Step 3: Move to index 2, read value 30

[0:10] -> [1:20] -> [2:30↑] -> [3:40] -> [4:50] -> null

Why: Keep moving forward to visit all elements

Step 4: Move to index 3, read value 40

[0:10] -> [1:20] -> [2:30] -> [3:40↑] -> [4:50] -> null

Why: Continue until last element

Step 5: Move to index 4, read value 50

[0:10] -> [1:20] -> [2:30] -> [3:40] -> [4:50↑] -> null

Why: Last element visited to complete traversal

Result:

[0:10] -> [1:20] -> [2:30] -> [3:40] -> [4:50] -> null
Printed values: 10 20 30 40 50

Annotated Code

DSA C

#include <stdio.h>

void traverseArray(int arr[], int size) {
    for (int i = 0; i < size; i++) {
        // print current element
        printf("%d ", arr[i]);
    }
    printf("\n");
}

int main() {
    int arr[] = {10, 20, 30, 40, 50};
    int size = sizeof(arr) / sizeof(arr[0]);
    traverseArray(arr, size);
    return 0;
}

for (int i = 0; i < size; i++) {

loop through each index from start to end

printf("%d ", arr[i]);

print the current element at index i

Output

10 20 30 40 50 

Complexity Analysis

Time: O(n) because we visit each of the n elements once

Space: O(1) because we use only a fixed amount of extra space

vs Alternative: Compared to random access, traversal is simple and direct with no extra cost

Edge Cases

empty array

loop does not run, nothing is printed

DSA C

for (int i = 0; i < size; i++) {

array with one element

prints the single element correctly

DSA C

for (int i = 0; i < size; i++) {

When to Use This Pattern

When you need to look at or use every item in a list one by one, use array traversal to visit each element in order.

Common Mistakes

Mistake: Using <= instead of < in the loop condition causing out-of-bounds access
Fix: Change loop condition to i < size to stay within array limits

Mistake: Starting loop index at 1 instead of 0, skipping first element
Fix: Start loop index at 0 to include the first element

Summary

It visits each element in an array one by one.

Use it when you want to process or read all items in order.

Remember to start at index 0 and stop before the array size.