[ADD CONTENT] C++ Basic Concepts

1_cpp_basics/arrays/arrays2d.cpp

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+#include<iostream>
+using namespace std; 
+int main( ) 
+{  
+	int arr[4][2] = {//An array with 4 rows and 2 columns is made and initialized
+		{ 10, 11 },
+		{ 20, 21 },
+		{ 30, 31 },
+		{ 40, 41 }
+		} ;
+
+	int i,j;//Two variables for looping
+
+	cout<<"Printing a 2D Array:\n";
+	for(i=0;i<4;i++)//traversing through row
+	{
+		for(j=0;j<2;j++)//traversing through column
+		{
+			cout<<"\t"<<arr[i][j];
+		}
+		cout<<endl;
+	}
+    return 0;
+} 

1_cpp_basics/arrays/passing2darraytofunction.cpp

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+#include<iostream>
+using namespace std;   
+
+void display(int (*ptr)[4], int  row, int  col) //Call by Address
+{
+	int  i, j ;
+	for(i=0;i<row;i++)
+	{
+		for(j=0;j<col;j++)
+    		cout<<"\t"<<*(*(ptr + i)+j); //Array is printed with help of pointer arithmetic
+		cout<<"\n";
+	}  
+    cout<<"\n";
+} 
+
+void print(int  ptr[][4], int row, int col)//Call by value
+{
+    int  i, j; 
+    for(i=0;i<row;i++)
+    {   
+	    for(j=0;j<col;j++)
+   	      cout<<"\t"<<ptr[i][j];
+   	  cout<<"\n";
+  	}
+   cout<<"\n";
+}
+
+int main() 
+{
+  int  a[3][4] = { 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21} ; 
+
+  display (a, 3, 4); 
+  print (a, 3, 4);
+  return 0;
+}

1_cpp_basics/classes_and_objects/classes_and_objects.cpp

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+// C++ program to demonstrate function
+// declaration outside class
+
+#include <iostream>
+using namespace std;
+class Sra
+{
+	public:
+	char first_letter;
+	int id;
+
+	// printletter is not defined inside class definition
+	void printletter();
+
+	// printid is defined inside class definition
+	void printid()
+	{
+		cout <<"SRA id is: "<<id;
+	}
+};
+
+// Definition of printletter using scope resolution operator ::
+void Sra::printletter()
+{
+	cout <<"First letter of my name  is: "<<first_letter;
+}
+int main() {
+
+	Sra obj1;
+	obj1.first_letter= 'v';
+	obj1.id=24;
+
+	// call printletter()
+	obj1.printletter();
+	cout << endl;
+
+	// call printid()
+	obj1.printid();
+	return 0;
+}

1_cpp_basics/conditional_statements/if.cpp

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+#include <iostream>
+using namespace std;
+int main()
+{
+  int num =10;
+  if(num>5) // condition 
+  {
+    cout<<"Hello From SRA\n";
+//If condn is fullfilled it will get executed
+  } 
+  return 0;
+}

1_cpp_basics/conditional_statements/if_else.cpp

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+//Code to find even and odd num using if else statement
+#include <iostream>
+using namespace std;
+int main()
+{
+  int num =10;
+  if(num%2 == 0)//if num is divisible by 2 i.e remainder is 0   when divided by 2
+  {
+    cout<<"the number is even\n";
+  }
+  else//if If statement is not satisfied the else statement is executed
+  {
+    cout<<"The number is odd\n";
+  }
+  return 0;
+}

1_cpp_basics/conditional_statements/switch.cpp

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+#include <iostream>
+using namespace std;
+int main()
+{
+int day = 4;
+switch (day) {//Switch statement with day given as condition for cases
+  case 1://If day=1 then case1 is executed
+    cout << "Monday";
+    break;//if case1 is executed then break is executed and exits switch statement
+  case 2://If day=2 then case2 is executed
+    cout << "Tuesday";
+    break;//if case2 is executed then break is executed and exits switch statement
+  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;
+   default:// If none of the case is satisfied then default statement is executed.
+   cout<<"Not a day";
+   break; 
+}
+return 0;
+}

1_cpp_basics/enumeration/enumeration.cpp

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+#include <iostream>
+using namespace std;
+
+enum seasons { spring = 34, summer = 4, autumn = 9, winter = 32};
+// enum named season is made and spring,summer ,autumn and winter are its member with values 34,5,9,32 respectively 
+int main() {
+
+    seasons s;// s is a variable of type seasons(enum)
+
+    s = summer;//s is assigned value of summer
+    cout << "Summer = " << s << endl;
+
+    return 0;
+}

1_cpp_basics/functions/function.cpp

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+#include <iostream>
+using namespace std;
+
+// Following function that takes two parameters 'x' and 'y'
+// as input and returns max of two input numbers
+int max(int x, int y)//max function made with return type int and parameters int x and int y
+{
+	if (x > y)
+		return x;
+	else
+		return y;
+}
+
+// main function that doesn't receive any parameter and
+// returns integer
+int main()
+{
+	int a = 10, b = 20;
+
+	// Calling above function to find max of 'a' and 'b'
+	int m = max(a, b);
+
+	cout << "m is " << m;
+	return 0;
+}

1_cpp_basics/namespace/namespace.cpp

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+#include <iostream>
+using namespace std;
+// first name space
+namespace first_space
+{
+void func()
+{
+	cout << "Inside first_space" << endl;
+}
+}
+
+// second name space
+namespace second_space
+{
+void func()
+{
+	cout << "Inside second_space" << endl;
+}
+}
+using namespace first_space;
+int main ()
+{
+// This calls function from first name space.
+func();
+return 0;
+}

1_cpp_basics/pointers/pointers.cpp

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+#include <iostream>  
+using namespace std;  
+int main()  
+{  
+    int number=30;    
+    int *p;      
+    p=&number;//stores the address of number variable    
+    cout<<"Address of number variable is:"<<&number<<endl;    
+    cout<<"Address of p variable is:"<<p<<endl;    
+    cout<<"Value of p variable is:"<<*p<<endl;    
+    return 0;  
+}  
+

1_cpp_basics/pointers/pointers_and_array.cpp

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+#include<iostream>
+using namespace std;
+/* Usage of pointer to an array */ 
+int main( ) 
+{  
+     int  a[4][2] = {  // Declaring and initialising a 2D array
+          {1, 2},
+          {1, 2},
+          {1, 2},
+          {1, 2}
+          } ;
+
+     int (*ptr)[2] ; //Declaring a 2D pointer
+     int  i, j;
+     for (i = 0 ; i <= 3 ; i++)
+     {
+     		ptr=&a[i]; //Stores the address of Array a with index i, in ptr
+     		cout<<"Row"<<i<<":";
+           for (j = 0; j <= 1; j++)
+               cout<<"\t"<<*(*ptr+j); //Prints the data at pointed by address ptr+j
+           cout<<endl;
+     } 
+   return 0;  
+}

1_cpp_basics/templates/class_template.cpp

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+    #include <iostream>  
+    using namespace std;  
+    template<class T>  //Declaring the Class template
+    class A   
+    {  
+        public:  
+        T num1 = 5;  
+        T num2 = 6;  
+        void add()  
+        {  
+            std::cout << "Addition of num1 and num2 : " << num1+num2<<std::endl;  
+        }  
+
+    };  
+
+    int main()  
+    {  
+        A<int> d;  
+        d.add();  //Calling the class method
+        return 0;  
+    } 

1_cpp_basics/templates/functional_template.cpp

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+//Example of Function Template
+
+#include <iostream>  
+using namespace std;  
+template<class T> T add(T &a,T &b)  //Declaring a Functional template
+{  
+    T result = a+b;  
+    return result;  
+
+}  
+int main()  
+{  
+  int i =2;  
+  int j =3;  
+  float m = 2.3;  
+  float n = 1.2;  
+  cout<<"Addition of i and j is :"<<add(i,j);  //Calling the template for integer data type
+  cout<<'\n';  
+  cout<<"Addition of m and n is :"<<add(m,n);  //Calling the template for float data type
+  return 0;  
+}

1_cpp_basics/typecasting/explicit_typecasting.cpp

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+// C++ program to demonstrate
+// explicit type casting
+
+#include <iostream>
+using namespace std;
+
+int main()
+{
+	float x = 1.2;
+
+	// Explicit conversion from double to int
+	int sum = (int)x + 1;
+
+	cout << "Sum = " << sum<<endl;
+
+	return 0;
+}

1_cpp_basics/typecasting/implicit_typecasting.cpp

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+// An example of implicit conversion
+
+#include <iostream>
+using namespace std;
+
+int main()
+{
+	int x = 10; // integer x
+	char y = 'a'; // character c
+
+	// y implicitly converted to int. ASCII
+	// value of 'a' is 97
+	x = x + y;
+
+	// x is implicitly converted to float
+	float z = x + 1.0;
+
+	cout << "x = " << x << endl
+		<< "y = " << y << endl
+		<< "z = " << z << endl;
+
+	return 0;
+}

1_cpp_basics/vectors/access_vector.cpp

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+#include <iostream>
+#include <vector>
+using namespace std;
+
+int main() {
+  vector<int> num {1, 2, 3, 4, 5}; //Initialised a vector
+
+  cout << "Element at Index 0: " << num.at(0) << endl; //Printing value at vector index 0
+  cout << "Element at Index 2: " << num.at(2) << endl; //Printing value at vector index 2
+  cout << "Element at Index 4: " << num.at(4); //Printing value at vector index 4
+
+  return 0;
+}