Structure of a C++ Program

What is a C++ program structure?

A C++ program follows a standard structure that helps the compiler understand and execute the code step by step.

Main parts of a C++ program

• 📌 Preprocessor directives
• 📌 Namespace declaration
• 📌 Main function
• 📌 Statements and logic

Basic structure example

#include <iostream>   // Preprocessor directive
using namespace std;   // Namespace

int main() {           // Main function
  cout << "Hello, World!";  // Output statement
  return 0;            // Program ends
}

Explanation of each part

1. Preprocessor directives

Lines starting with # are processed before compilation. Example: #include <iostream>.

2. Namespace

namespace std avoids naming conflicts and allows use of standard library features.

3. main() function

This is the entry point of every C++ program. Execution starts here.

4. Statements

These are instructions written inside main() that define program behavior.

Why structure matters

• Makes code readable
• Helps compiler understand program flow
• Improves debugging and maintenance

Summary

A C++ program is built using preprocessor directives, namespaces, the main function, and executable statements. All execution begins from main().