Hello World
Compile Command
Using GNU, the compilation command is g++ followed by the file name. Here, the name of the source file is hello.cpp.
g++ hello.cpp
Execute Command
The execution command is ./ followed by the file name. Here, the name of the executable file is a.out.
./a.out
Single-line Comments
Single-line comments are created using two consecutive forward slashes. The compiler ignores any text after // on the same line.
// This line will denote a comment in C++
Multi-line Comments
Multi-line comments are created using /* to begin the comment, and */ to end the comment. The compiler ignores any text in between.
/*This is all commented out.None of it is going to run!*/
Program Structure
The program runs line by line, from top to bottom:
- The first line instructs the compiler to locate the file that contains a library called
iostream. This library contains code that allows for input and output. - The
main()function houses all the instructions for the program.
#include <iostream>int main() {std::cout << "1\n";std::cout << "2\n";std::cout << "3\n";}
Basic Output
std::cout is the “character output stream” and it is used to write to the standard output. It is followed by the symbols << and the value to be displayed.
std::cout << "Hello World!\n";
New Line
The escape sequence \n (backward slash and the letter n) generates a new line in a text string.
std::cout << "Hello\n";std::cout << "Hello again\n";
