Basics

 

Introduction

What is C++?

C++ is a widely used programming language that works on different types of computer systems.

It’s used to create all sorts of software, from video games and mobile apps to operating systems and even the software that runs on cars and appliances.

Many tech interviews involve C++ due to its strong performance, making it a valuable skill to have.

Basic Syntax:

#include<iostream>
int main() {
// ... code ....
return 0;
}.

Here’s a breakdown of each component:

is a standard library that provides basic input and output services.

int main() { … }

where the program’s execution starts.

a return value of 0 from main typically indicates that the program executed successfully.

Important Points:

->Every line in C++ is ending with semicolon ;.
-> Do not forget to add the closing curly bracket } to actually end the main function.
-> The endl keyword serves the purpose of moving to a new line

moyasite
-> using namespace std can simplify code writing by eliminating the need to prefix each line with std::.
-> #include <bits/stdc++.h> contains all standard libraries of the header files. So if you include it in your code, then you need not have to include any other standard header files.

Comments in C++

Single line comment

// single line comment

Multi line comment

/*
Multi line comment
*/

Hello World Program

#include <bits/stdc++.h>
int main(){
std::cout << "Hello World!"; // Output - Hello World!
return 0;
} 

This line uses the cout
object to print the text “Hello World!” to the standard output.
It is part of the C++ Standard Library’s input/output stream
(iostream) and is used for output operations.

Input and Output in C++

#include <bits/stdc++.h>
using namespace std;
int main(){
int a;
cin >> a; // Input - 5
cout << a*5 << endl; // Output - 25
return 0;
} 

Using cin:
cin reads and accepts only the first word from the input.

#include <bits/stdc++.h>
using namespace std;
int main(){
string s;
cin >> s; // Input - Hello World
cout << s; // Output - Hello
return 0;
} 

Using getline:
To take a sentence as input, you can use getline(cin, string_name)..

#include <bits/stdc++.h>
using namespace std;
int main(){
string s;
getline(cin, s); //Input - Hello World!
cout << s; //Output - Hello World!
return 0;
} 

Conditional Statements:
Control statements in programming are like instructions that tell the computer what to do based on certain conditions. It’s like making a decision. If something is true, do one thing; if it’s false, do something else.
Following are the some decision-making statements:
if Statement:
The if statement is a decision-maker that executes a block of code if a specified condition is true and skips it if the condition is false.

Syntax:

if(condition)
{
// Statements to execute if
// condition is true
} 

if-else Statement

The if-else statement consists of two blocks, one for false expression and one for true expression.

Syntax:

if (condition)
{
// Executes this block if
// condition is true
}
else
{
// Executes this block if
// condition is false
}

if-else-if Ladder

Use if-else if statements to choose from multiple options, executed sequentially; when a true condition is found, it’s executed, or the final else statement is executed if none are true.

Syntax:

if (condition)
{
// statements
}
else if (condition)
{
// statements
}
else{
// statements
}

Switch Statement:

The switch-case statement lets you choose between different code blocks based on a variable’s value, providing an alternative to a series of if-else if checks.

Syntax:

switch (expression) {
case value1:
statements;
case value2:
statements;
....
....
default:
statements;
}

Strings

Strings are sequences of characters used to represent text or data in programming. In C++, you can work with strings using the