cheat sheet of C++

#include<bits/stdc++.h>
using namespace std;

/*this is the basic for printing variable Initialization
int main(){
    int hg,x;
    cin>>x>>hg;
    cout<<"X= "<<x<<"\n";
    cout<<"Hg= "<<hg;
    return 0;
}
*/
/*local variable
int p(){
    int m=77;
    cout<<"the value of m is : "<<m;

}
int main(){
    cout<<"Marks: ";
    p();
    return 0;
}
*/
/*global variable
int glob=77;
int p(){
    cout<<"the global value is:"<<glob<<endl;

}
int main(){
    p();//the value is 32
    glob=55;
    p();//the glob value is updated to 55
    return 0;
}
*/
/*datatypes
int main(){
    int i=10;cout<<i<<endl;
    short s=1;cout<<s<<endl;
    long l=1000;cout<<l<<endl;
    long long ll=10;cout<<ll<<endl;
    float f=10.1;cout<<f<<endl;
    double d=10.123;cout<<d<<endl;
    long double ld=10.1538;cout<<ld<<endl;
    
}
*/
//Control statements - if else
/*
int main(){
    int age;
    cout<<"enter age"<<endl;
    cin>>age;
if(age>=18){
    cout<<"DL ok";
}
else{
    cout<<"DL not ok";
}
}
//else-if statement
int main(){
    int age;
    cout<<"enter age"<<endl;
    cin>>age;
if(age>118||age<1){
    cout<<"DL invalid";
}
else if(age>=18){
    cout<<"DL ok";
}
else{
    cout<<"DL not ok";
}
}
*/
/*switch case
int main(){
int age;
cout<<"enter age: ";
cin>>age;
switch (age)
{
case 18:cout<<"Eligible";
       break;
case 12:cout<<"not eligible";
        break;
case 50:cout<<"out of range";        
default:cout<<"not available";
    break;
}
}
*/
/*for loop
int main(){
    int i,n=10;
    for(i=0;i<n;i++)
    {
        cout<<"i="<<i<<"\n";
        
    }
    
}
*/
/*while loop
int main(){ 
    int i=0;
while(i<5)
    { 
        cout<<"S"<<i<<"\n";
        i++;
    }
    }
*/
/*do while
int main(){
    int n;

    do{
        cout<<"enter n"<<endl;
        cin>>n;
    }while(n!=0);
}
*/
//arrays 
/* 1D array
int main(){
    int a[5],i;
    for( i=0;i<5;i++){
        cout<<"Enter element "<<"\t";
        cin>>a[i];
}
for(i=0;i<5;i++){
    cout<<a[i]<<"\t";
}
}
*/
//2D array
/*
int main(){
    int i,j;
    int a[3][3]= {{1,2,3},{4,5,6},{7,8,9}};
    //displaying elements of the array using nested loops
    for(i=0;i<3;i++){
        for(j=0;j<3;j++){
            cout<<"element at "<<i<<","<<j<<" is "<<a[i][j]<<endl;
        }
    }
}
*/
//functions
/*
int add(int a,int b)
{
    return (a+b);
}
int main(){
    cout<<"sum is "<<add(2,6);
}
*/
//function overloading
/*
int sub(int a,int b){
return a-b;
}
double sub(double a,double b){
return a-b;
}
int main(){
cout<<sub(10,7)<<endl;
cout<<sub(5.25,3.66);
}
*/
//pointers
/*
int main(){
int x= 5;
int *ptr; //ptr is a pointer
ptr= &x; // Storing address of x in ptr
cout<<ptr<<endl; // address of pointer
cout<<*ptr<<endl;
cout<<x; // value stored by the pointer
cout<<&x<<endl; //address of x
}
*/
//classes
/*
class stu{
    public:string usn;
    string name;
};
int main(){
    stu s1;
    s1.usn="A1";
    s1.name="Ankit";
    cout<<s1.name<<"\n"<<s1.usn;
}
*/
//constructor
/*
class stu{
    public:string usn;
    string name;
    stu(string n,string u)
    {
        name=n;
        usn=u;
    }
};
int main(){
    stu s1= stu( "Ankita", "A1");
   cout<<s1.name<<"\n";
   stu s2= stu( "nakita", "B2");
   cout<<s2.name<<"\n";
    }
   */
/*Inheritance
class up{
    public: int a=1;

};
class down:public up{
    public: int b=2;
};
int main(){
    down d;
    cout<<"the down is "<<d.b<<endl;
    cout<<"the up is "<<d.a<<endl;
}
*/
/*Pass by value
int smthg(int num){
num += 1;
cout<<num<<endl;
num += 1;
cout<<num<<endl;
num += 1;
cout<<num<<endl;
}

int main(){
    int num;
    cin>>num;
    smthg(num);
    cout<<num;
}
//Pass by reference
int smthg(int &num){
num += 1;
cout<<num<<endl;
num += 1;
cout<<num<<endl;
num += 1;
cout<<num<<endl;
}

int main(){
    int num;
    cin>>num;
    smthg(num);
    cout<<num;
}
*/
//Pass by reference - array
#include<bits/stdc++.h>
using namespace std;

/*this is the basic for printing variable Initialization
int main(){
    int hg,x;
    cin>>x>>hg;
    cout<<"X= "<<x<<"\n";
    cout<<"Hg= "<<hg;
    return 0;
}
*/
/*local variable
int p(){
    int m=77;
    cout<<"the value of m is : "<<m;

}
int main(){
    cout<<"Marks: ";
    p();
    return 0;
}
*/
/*global variable
int glob=77;
int p(){
    cout<<"the global value is:"<<glob<<endl;

}
int main(){
    p();//the value is 32
    glob=55;
    p();//the glob value is updated to 55
    return 0;
}
*/
/*datatypes
int main(){
    int i=10;cout<<i<<endl;
    short s=1;cout<<s<<endl;
    long l=1000;cout<<l<<endl;
    long long ll=10;cout<<ll<<endl;
    float f=10.1;cout<<f<<endl;
    double d=10.123;cout<<d<<endl;
    long double ld=10.1538;cout<<ld<<endl;
    
}
*/
//Control statements - if else
/*
int main(){
    int age;
    cout<<"enter age"<<endl;
    cin>>age;
if(age>=18){
    cout<<"DL ok";
}
else{
    cout<<"DL not ok";
}
}
//else-if statement
int main(){
    int age;
    cout<<"enter age"<<endl;
    cin>>age;
if(age>118||age<1){
    cout<<"DL invalid";
}
else if(age>=18){
    cout<<"DL ok";
}
else{
    cout<<"DL not ok";
}
}
*/
/*switch case
int main(){
int age;
cout<<"enter age: ";
cin>>age;
switch (age)
{
case 18:cout<<"Eligible";
       break;
case 12:cout<<"not eligible";
        break;
case 50:cout<<"out of range";        
default:cout<<"not available";
    break;
}
}
*/
/*for loop
int main(){
    int i,n=10;
    for(i=0;i<n;i++)
    {
        cout<<"i="<<i<<"\n";
        
    }
    
}
*/
/*while loop
int main(){ 
    int i=0;
while(i<5)
    { 
        cout<<"S"<<i<<"\n";
        i++;
    }
    }
*/
/*do while
int main(){
    int n;

    do{
        cout<<"enter n"<<endl;
        cin>>n;
    }while(n!=0);
}
*/
//arrays 
/* 1D array
int main(){
    int a[5],i;
    for( i=0;i<5;i++){
        cout<<"Enter element "<<"\t";
        cin>>a[i];
}
for(i=0;i<5;i++){
    cout<<a[i]<<"\t";
}
}
*/
//2D array
/*
int main(){
    int i,j;
    int a[3][3]= {{1,2,3},{4,5,6},{7,8,9}};
    //displaying elements of the array using nested loops
    for(i=0;i<3;i++){
        for(j=0;j<3;j++){
            cout<<"element at "<<i<<","<<j<<" is "<<a[i][j]<<endl;
        }
    }
}
*/
//functions
/*
int add(int a,int b)
{
    return (a+b);
}
int main(){
    cout<<"sum is "<<add(2,6);
}
*/
//function overloading
/*
int sub(int a,int b){
return a-b;
}
double sub(double a,double b){
return a-b;
}
int main(){
cout<<sub(10,7)<<endl;
cout<<sub(5.25,3.66);
}
*/
//pointers
/*
int main(){
int x= 5;
int *ptr; //ptr is a pointer
ptr= &x; // Storing address of x in ptr
cout<<ptr<<endl; // address of pointer
cout<<*ptr<<endl;
cout<<x; // value stored by the pointer
cout<<&x<<endl; //address of x
}
*/
//classes
/*
class stu{
    public:string usn;
    string name;
};
int main(){
    stu s1;
    s1.usn="A1";
    s1.name="Ankit";
    cout<<s1.name<<"\n"<<s1.usn;
}
*/
//constructor
/*
class stu{
    public:string usn;
    string name;
    stu(string n,string u)
    {
        name=n;
        usn=u;
    }
};
int main(){
    stu s1= stu( "Ankita", "A1");
   cout<<s1.name<<"\n";
   stu s2= stu( "nakita", "B2");
   cout<<s2.name<<"\n";
    }
   */
/*Inheritance
class up{
    public: int a=1;

};
class down:public up{
    public: int b=2;
};
int main(){
    down d;
    cout<<"the down is "<<d.b<<endl;
    cout<<"the up is "<<d.a<<endl;
}
*/
/*Pass by value
int smthg(int num){
num += 1;
cout<<num<<endl;
num += 1;
cout<<num<<endl;
num += 1;
cout<<num<<endl;
}

int main(){
    int num;
    cin>>num;
    smthg(num);
    cout<<num;
}
Pass by reference
void smthg(int a[], int n){
    a[0]+=50;
    cout<<"value inside smthg function "<<a[0]<<endl;
}

int main(){
    int n=5;
    int a[n];
    for  (int i = 0; i < n ; i++) {
    cin>>a[i];
    }
    smthg(a,n);
    cout<<"value inside int main "<<a[0];
}
*/