Data Structures in C/C++

Singly Linked List

Each node stores a value and a link to the next node, allowing insertion without shifting contiguous elements.

What is Singly Linked List?

Each node stores a value and a link to the next node, allowing insertion without shifting contiguous elements.

Build, traverse, and destroy a linked list.

Important points

State the invariants before implementing operations.
Handle empty, full, and allocation-failure cases.
Measure time complexity and memory ownership together.

C and C++ code examples

Run code →

main.c

#include <stdio.h>
#include <stdlib.h>

typedef struct Node {
    int value;
    struct Node *next;
} Node;

int main(void) {
    Node *head = NULL;
    for (int value = 3; value >= 1; --value) {
        Node *node = malloc(sizeof *node);
        if (!node) return 1;
        *node = (Node){value, head};
        head = node;
    }
    while (head) {
        Node *next = head->next;
        printf("%d ", head->value);
        free(head);
        head = next;
    }
    puts("");
    return 0;
}

Expected output

1 2 3

C++

Run code →

main.cpp

#include <iostream>
#include <memory>

struct Node {
    int value;
    std::unique_ptr<Node> next;
};

int main() {
    std::unique_ptr<Node> head;
    for (int value = 3; value >= 1; --value) {
        head = std::make_unique<Node>(Node{value, std::move(head)});
    }
    for (Node *node = head.get(); node; node = node->next.get()) {
        std::cout << node->value << ' ';
    }
    std::cout << '\n';
}

Expected output

1 2 3

C and C++ comparison

The C version owns nodes through malloc and must free every node. The C++ version uses unique_ptr so destroying the head recursively releases the chain.

Structures and operations are usually separate and allocation is explicit.

C++

Classes and containers can preserve invariants and manage resources automatically.

Practice exercises

Run both versions, then modify them to observe the different language guarantees.

Add empty and capacity-boundary tests.
Implement cleanup and verify no leaks remain.
Compare operation complexity with a standard container.