C++ cheat sheet programs for Beginner and Competitive Exams

cplus.cpp

// A Simple hello world
/*
Note:C++ is case-sensitive. So, expect compilation to fail if you write
Int instead of int and Std::Cout instead of std::cout.
*/
  
#include<iostream>
int main(){
std::cout<<"Hello World!"<<std::endl;
}

cplus01.cpp

// Understanding Namespace
// Preprocessor directive
#include <iostream>

// Start of your program
int main()

{
 
// Tell the compiler what namespace to search in
using namespace std;
/*

Write to the screen using std::cout 

*/
cout << "Hello World" << endl;

// Return a value to the OS
return 0;
}

cplus02.cpp

//Declaring, Defining, and Calling a Function That Demonstrates Capabilities

of std::cout
#include <iostream>
using namespace std;

 // Declare a function
 int DemoConsoleOutput();

 int main()
 {
// Call i.e. invoke the function
 DemoConsoleOutput();

 return 0;
 }

 // Define i.e. implement the previously declared function
 int DemoConsoleOutput()
 {
 cout << "This is a simple string literal" << endl;
 cout << "Writing number five: " << 5 << endl;
 cout << "Performing division 10 / 5 = " << 10 / 5 << endl;
 cout << "Pi when approximated is 22 / 7 = " << 22 / 7 << endl;
 cout << "Pi is 22 / 7 = " << 22.0 / 7 << endl;

 return 0;
 }

cplus03.cpp

//C++ Flow Control

/*
There are three forms of if...else statements in C++.

if statement
if...else statement
if...else if...else statement

*/
/*
if (condition) {
   // body of if statement
}

if...else statement

if (condition) {
    // block of code if condition is true
}
else {
    // block of code if condition is false
}

-- if...else if...else statement

if (condition1) {
    // code block 1
}
else if (condition2){
    // code block 2
}
else {
    // code block 3
}
*/
#include<iostream>
using namespace std;

int main(){

    int num;
    cout<<"Input a Number"<<endl;
    cin>>num;
    if(num>=0){
        cout<<"Positive Number"<<endl;
    }else
    {
        cout<<"Negative Number"<<endl;
    }
}

cplus04_switch.cpp

switch(expression) {
  case x:
    // code block
    break;
  case y:
    // code block
    break;
  default:
    // code block
}

int day = 4;
switch (day) {
  case 1:
    cout << "Monday";
    break;
  case 2:
    cout << "Tuesday";
    break;
  case 3:
    cout << "Wednesday";
    break;
  case 4:
    cout << "Thursday";
    break;
  case 5:
    cout << "Friday";
    break;
  case 6:
    cout << "Saturday";
    break;
  case 7:
    cout << "Sunday";
    break;
}
// Outputs "Thursday" (day 4)

cplus05_function.cpp

//Function in c plus

/*
There are two types of function:

1.Standard Library Functions: Predefined in C++
2. User-defined Function: Created by users
Below is the example of user defined function
*/

#include <iostream>
using namespace std;

// declaring a function
void heyReader() {
    cout << "Hello there! Thank You for reading this section";
}

int main() {

    // calling the function
    heyReader();

    return 0;
}

cplus06_loops.cpp

//In computer programming, loops are used to repeat a block of code.

/*
There are 3 types of loops in C++.

for loop
while loop
do...while loop

*/
//FOR LOOP
for (initialization; condition; update) {
    // body of-loop 
}


//WHILE LOOP
while (condition) {
    // body of the loop
}

//DO-WHILE  LOOP
do {
   // body of loop;
}
while (condition);



//infinite loop example
#include <iostream>
using namespace std;
int main() {
    // Write C++ code here
   for(int i=1;i>0;i++){
       cout<<"hacked!"<<endl;
   }

    return 0;
}

cplus07_array.cpp

//In C++, the size and type of arrays cannot be changed after its declaration.

/*

syntax :
dataType arrayName[arraySize];

declare and initialize and array
int x[6] = {19, 10, 8, 17, 9, 15};

// declare and initialize an array
int x[] = {19, 10, 8, 17, 9, 15};
*/


//EXAMPLE - Take Inputs from User and Store Them in an Array


#include <iostream>
using namespace std;

int main() {
    int numbers[5];

    cout << "Enter 5 numbers: " << endl;

    //  store input from user to array
    for (int i = 0; i < 5; ++i) {
        cin >> numbers[i];
    }

    cout << "The numbers are: ";

    //  print array elements
    for (int n = 0; n < 5; ++n) {
        cout << numbers[n] << "  ";
    }

    return 0;
}

cplus08_pointer.cpp

//POINTER

/*
Pointers are used for file handling. Pointers are used to allocate memory dynamically. 
In C++, a pointer declared to a base class could access the object of a derived class. 
However, a pointer to a derived class cannot access the object of a base class.

*/

#include <iostream>
using namespace std;
int main() {

    int age=21;
    int* agePointer;
    agePointer=&age;
    cout<<agePointer;
    return 0;
}