Structure of a C++ Program

reading

• Structure of a program from cplusplus.com

Let’s look at a simple “Hello, World” program:

Important

Every C++ program needs to have a main() function

#include <iostream>

// our Hello, World program

int main()
{
   std::cout << "Hello World!" << std::endl;
}

A nice breakdown of a “Hello, World” program is shown here: https://www.cplusplus.com/doc/tutorial/program_structure/ —let’s walk through that.

A few important bits:

• A preprocessor is used to bring additional functionality into our code (the #include)

• C++ comments start with //

• Each C++ program needs to have a function called main() and that function is of type int.

• { and } are used to denote blocks of code in C++

• The C++ Standard Library provides a lot of useful functions and capabilities. Here we use std::cout from the standard library to output.

• << is an operator in C++. Its meaning can depend on context. Here it is used to pass "Hello, World!" to cout

• :: is the scope operator. This tells us that cout is part of a namespace called std, and the compiler should look there for its implementation.

• Statements end with ;

Note

C++ files can have a variety of extensions, including: .C, .cxx, .cc, and .cpp.

I’ll use .cpp throughout this course.