C++ Syntax

C++ Program Structure

Every C++ program follows a basic structure. Let us look at the parts:

#include <iostream>       // 1. Include libraries
using namespace std;       // 2. Use the standard namespace

int main() {               // 3. Main function — entry point
    cout << "Hello!";     // 4. Statement
    return 0;              // 5. Return value
}

Statements and Semicolons

Every statement in C++ must end with a semicolon (;). Missing semicolons are one of the most common beginner errors.

cout << "Line one";    // correct
cout << "Line two"     // ERROR: missing semicolon

Whitespace and Indentation

C++ ignores extra spaces, tabs, and newlines. They are used only to make code readable. The two programs below are identical to the compiler:

// Readable
int main() {
    cout << "Hello";
    return 0;
}

// Minified (valid but unreadable)
int main(){cout<<"Hello";return 0;}

Full Example

#include <iostream>
using namespace std;

int main() {
    cout << "C++ Syntax is simple!" << endl;
    cout << "Each statement ends with a semicolon." << endl;
    return 0;
}

Output:

C++ Syntax is simple!
Each statement ends with a semicolon.

#include <iostream>
using namespace std

int main()
    cout << "Fix me!" << endl
    return 0;
}

#include <iostream>
using namespace std;    // added semicolon

int main() {            // added opening brace
    cout << "Fix me!" << endl;  // added semicolon
    return 0;
}

Summary

• A C++ program starts with #include directives and a main() function.
• Every statement must end with a semicolon.
• Code blocks are enclosed in curly braces { }.
• Whitespace is ignored by the compiler but important for readability.