C++ · Chapter 3 of 49
C++ Get Started
Every C++ program needs a `main()` function — this is where execution begins. The program returns an integer exit code, usually 0 to mean success.
Headers like `<iostream>` are included with `#include` so you can use library features such as input/output.
Anatomy of a program
`#include <iostream>` brings in the I/O library. `int main() { ... }` is the entry point. Statements inside main run in order, and `return 0;` ends the program successfully.
Compiling and running
Save the file with a `.cpp` extension, compile it with g++, then execute the produced binary. Any compiler errors must be fixed before you get an executable.
Example 1 (cpp)
#include <iostream>
int main() {
std::cout << "Hello from main!" << std::endl;
return 0;
}Output
Hello from main!std::endl prints a newline and flushes the output buffer.
Key points
- Every program needs exactly one main() function.
- main() typically returns an int (0 = success).
- #include brings library code into your file.
- Statements execute top-to-bottom inside main.
💡 Note: Returning 0 from main is optional in C++ (it defaults to 0), but writing it explicitly is good practice.