C++ Basics — Part I (for beginner’s)
By: Aditya Agrawal
Tags: Technical, Students, Programming, Programming Club, Nit Raipur

C++ is a general-purpose programming language.

(and a lot more)

Before diving into code you must have compiler installed in your system.

Compiler — A program that converts High Level Language(HLL) into Low Level Language (LLL).

HLL :

int fib(int n) { int store[n+2];



store[0] = 1;

store[1] = 1; int i;

for(i=2;i<n;i++) {

store[i] = store[i-1] + store[i-2];

} return store[n-1];

} // Any language that you can code in, and is very close to "English" (a natural language) which is easy for a human to read, write and understand.

LLL :

mov edx, [esp+8]

cmp edx, 0

ja @f

mov eax, 0

ret // Commands or functions in the language map closely to processor instructions.

Windows Users : Install CodeBlocks (IDE) from here

Linux Users : Install g++ (highly recommended) and a CodeEditor (Sublime or VSCode)

Lazy Users : (yes lazy) : Can use online IDE’s , hackerearth, ideone .. etc. “I recommend you to always refrain from online IDE’s especially during a contest”

before we start, you must know that a C++ file has extension ‘cpp’, while a C file has extension ‘c’.

Let’s Start

#include<iostream>

using namespace std; int main() {

// A simple program to print "Hello World"

cout<<”Hello World!”;

return 0;

} Output: Hello World!

Now with explanation

#include<iostream> // iostream is a header file, it contains

// definition of cin & cout

using namespace std; // if this were not used then we'd have to

// write std::cout<<"abcd"; in the program

int main() { // declaration of function with name

// 'main' and return type of integer.

// the definition is found within "{}"

cout<<"Hello World!"; // cout prints output on the terminal

// notice - '<<' this is an operator

// notice - '//' statements beginning with

// these characters do not get executed,

// they are used for comments

return 0; // function main would return 0

// (an integer)

}

Let’s Math

#include<iostream>

using namespace std; int main() {

cout << "3 + 2 = " << 3+2 << endl;

cout << "3 - 2 = " << 3-2 << endl;

cout << "3 * 2 = " << 3*2 << endl;

cout << "3 / 2 = " << 3/2 << endl;

cout << "10 / 3 = " << 10/3 << endl;

cout << "10.0 / 3 = " << 10.0/3 << endl; return 0;

} OUTPUT :

3 + 2 = 5

3 - 2 = 1

3 * 2 = 6

3 / 2 = 1

10 / 3 = 3

10.0 / 3 = 3.33333

Notice 3 / 2 = 1 and 10 / 3 = 3, yes you guessed it correct, only the integral part is retained.

This happens because by default data-type is integer. Unless specified like in example 10.0 / 3 = 3.33333 (any operation that includes a decimal will result in one)

Book : Balaguruswamy OOPs with C++ (recommended)

Please go through chapter 3, 4 for a detailed content.

“Recommended”

All the chapters are important and would be covered in your course in span of one to two semesters. I cannot cover everything in this blog hence provided you with a resource.

Topics that you must know before moving forward are:

Variables (data type) Loops (for, while, do) IF ELSE Arrays & Matrix Functions

Important: To learn C/C++ you must read a book and run your code.

There is no other easy way.

(do not watch videos for this, start reading the book)

The next part would focus on getting a good grip on the language.