Control Structure

Control Structures in C++

The work of control structures is to give flow and logic to a program. There are three types of basic control structures in C++.

1.    Sequence Structure

Sequence structure refers to the sequence in which program execute instructions one after another.

                                        

 

                                 Figure 1: Sequence Structure

 

 

2.    Selection Structure

Selection structure refers to the execution of instruction according to the selected condition, which can be either true or false. There are two ways to implement selection structures, by “if-else statements” or by “switch case statements”. 

 

                                        Figure 2: Selection Structure

If else statement

The if/else statement executes a block of code if a specified condition is true. If the condition is false, another block of code can be executed.

    Switch Case Statements in C++

In switch-case statements, the value of the variable is tested with all the cases. Switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each case. For char use single inverted comma ‘ ‘.

#include <iostream>

using namespace std;

 

int main () {

         

   int day;

   cout<<"enter a number for print day  ";

   cin>>day;

 

   switch(day) {

      case 1 :

         cout << "Monday \n";

         break;

     

      case 2 :

         cout << "Tuesday \n";

         break;

      case 3 :

         cout << "Wednesday \n";

         break;

      case 7 :

      cout << "sunday \n";

         break;

      default :

         cout << "Invalid number \n";

   }  

 

   return 0;

}

 

3.    Loop Structure

Loop structure refers to the execution of an instruction in a loop until the condition gets false.

 

                                            Figure 3: Loop Structure

 

 

 Continue Statement in C/C++

Continue is also a loop control statement just like break statement. continue statement is opposite to that of break statement, instead of terminating the loop, it forces to execute the next iteration of the loop.
As the name suggest the continue statement forces the loop to continue or execute the next iteration. When the continue statement is executed in the loop, the code inside the loop following the continue statement will be skipped and next iteration of the loop will begin.

Example:
Consider the situation when you need to write a program which prints number from 1 to 10 and but not 6. It is specified that you have to do this using loop and only one loop is allowed to use.
Here comes the usage of continue statement. What we can do here is we can run a loop from 1 to 10 and every time we have to compare the value of iterator with 6. If it is equal to 6 we will use the continue statement to continue to next iteration without printing anything otherwise we will print the value.

 

 

#include <iostream>

Using namespace std;

  

int main() {

    // loop from 1 to 10 

    for (int i = 1; i <= 10; i++)

{

        if (i == 6) 

            continue; 

        else

    cout<<i<<”\t”;

    } 

    return 0; 

}

Output:

1            2            3            4            5           7            8           9           10

Pointer

A pointer however, is a variable that stores the memory address as its value.

A pointer variable points to a data type (like int or string) of the same type, and is created with the * operator. The address of the variable you're working with is assigned to the pointer:

Example

Main()

{

string food = "Pizza";  // A food variable of type string
string* ptr = &food;    // A pointer variable, with the name ptr, that stores the address of food

// Output the value of food (Pizza)
cout << food << "\n";

// Output the memory address of food (0x6dfed4)
cout << &food << "\n";

// Output the memory address of food with the pointer (0x6dfed4)
cout << ptr << "\n";

return 0;

}