Introduction to C++

This is a basic introduction where we learn how to output Hello World! and see the differences between Python and C++

Main difference in running C++ and Python

So if you are familiar with python, you know we can easily create a file called hello.py and simply run it with python hello.py
However for C++, we’ve 1 more step: compiling!
- Create the file hello.cpp
- Compile: g++ hello.cpp -o hello
- Run: ./hello

You would notice it’s less intuitive compared to Python, but nonetheless similar.

We use // for comments
Lines beginning with # are preprocessor commands
- #include: tells preprocessor to dump contents in another file
- <iostream>: file we’re dumping into that defines our IO
int main() defines the code when the program starts
- {}: multiple commands in a block
- Think of this as similar to defining a function in Python
:: is the scope resolution operator
- It tells the compiler to look for the identifier we want in the namespace (directory of identifiers)
cout <<: is the syntax for outputting text
- Intuitively, anything after <<: flows to cout that prints!
- On the other hand, we can get user’s input with cin >>:, see how the data flows in the opposite direction?
In the {} block, you must always use a ; after every line.
- This is a common mistake I made when I first started out.

We can test the file by running where variable.cpp is the file we saved our above code into:

g++ variable.cpp -o variable
./variable

Tags: