Introduction to C Programming

Table of Contents

1. Hello World

Hello World

As per programming traditions, our first program will be to print out "hello world" in the Terminal

Code : 01_hello_world.c

• Header Files

  We start by importing standard input/output header file. This includes the functions we require to print out on the screen. Learn more

  #include<stdio.h>
  

• Function

  • The 'main' function is a primary function in C code, it is the starting point for execution.
  • The function has various return types: void, int, float and more. In case, we return a wrong type we get a compilation error.
  • If we have to mention arguments to the function, we add them in the parenthesis '( )' after the function name. (In our program, currently no paramters are required)
  • The statements inside the function are enclosed in curly brackets '{ }'
  • Since our function is an 'int' type, we need to return some integer at the end of function.
  • We are returning 0 (Returning 0 indicates successful execution)

• Statements (printf)

  • We use printf function to print out characters on the Terminal
  • We are passing the string enclosed in quotes " " as an argument to the printf function.
  • We end each statement in C with a semi-colon ';'

Compiling the program

• C Programs need to be compiled first, to get an executable file.
• These compilations are handled by a compiler like gcc.
• To install gcc on Windows, watch this
• It is preinstalled on Mac and Linux.

To compile the program on a Mac, we run the following command:

gcc 01_hello_world.c -o 01_hello_world.out

And to run the executable we run 01_hello_world.out in Terminal:

./01_hello_world.out

We should get the output like:

Hello World