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Data Structures in C/C++

struct in C and class in C++

Model related state and behavior.

What is struct in C and class in C++?

C structs group data; C++ classes can enforce invariants by combining private state with member functions.

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

C
Run code →
main.c
#include <stdio.h>

typedef struct {
    const char *owner;
    double balance;
} Account;

void deposit(Account *account, double amount) {
    if (amount > 0) {
        account->balance += amount;
    }
}

int main(void) {
    Account account = {"Ada", 100.0};
    deposit(&account, 25.0);
    printf("%s: %.2f\n", account.owner, account.balance);
    return 0;
}
Result of running the code
Ada: 125.00
C++
Run code →
main.cpp
#include <iomanip>
#include <iostream>
#include <string>
#include <utility>

class Account {
    std::string owner_;
    double balance_;

public:
    Account(std::string owner, double balance)
        : owner_(std::move(owner)), balance_(balance) {}

    void deposit(double amount) {
        if (amount > 0) {
            balance_ += amount;
        }
    }

    void print() const {
        std::cout << owner_ << ": " << std::fixed
                  << std::setprecision(2) << balance_ << '\n';
    }
};

int main() {
    Account account("Ada", 100.0);
    account.deposit(25.0);
    account.print();
}
Result of running the code
Ada: 125.00

C and C++ comparison

The C design passes a struct pointer to functions. The C++ class keeps balance private and exposes operations, making invalid direct state changes harder.

C

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.

Practice with a challenge

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