Skip to main content

Looping Statements in Computer Programming, C Language

Introduction

We have learnt about branching statements that transfer the control from one point to another point in the computer programming. In this article, we concentrate on another important constructs like loop statements, which executes a set of statements repeatedly. Sometimes, it is required to execute a set of statements repeatedly in c programming. In such cases, the looping statements are used.

The statements that enables the programmer to execute a set of statements repeatedly till the required activity is completed, called looping statements or simply loop statements. These statements are also called repetitive or iterative statements. The statements within a loop may be executed for a fixed number of times or until a certain condition is reached. The various types of loop statements that are supported by the C language are as follows:

For Loop

A set of statements may have to be repeatedly executed for a specified number of times. In such situations, we use for loop statement. This type of loop is defined as an iterative statement that causes a set of statements to be executed repeatedly for a fixed number of times. If we know well in advance as how many times a set of statements have to be executed repeatedly, then for loop is the best choice.

The syntax of for loop as follows:
for (initialization; condition; increment/decrement)
{
    statement1;
    statement2;
    statement3;
}

Where

  • for: is the reserve word or keyword
  • Initialization: used to provide starting value to the variable. It should end with semicolon (;).
  • Condition: used to determine whether value of variable has reached the number of repetitions desired. It should end with semicolon (;).
  • Increment/Decrements: It is used to update the variable value by increment or decrements.

Note: Initialization, condition and updating statement can be multiple statements separated by comma (,).

In for loop some points have to keep in mind by c programmer, which are:

  • The initialization statement executes first and only once when the execution begins.
  • After this, condition is executed. If the condition is evaluated as the True then the body of for loop is executed. After executing the body of the loop the increment/decrements statement is executed. It is normally update the variable value by the specified step size. Then termination condition statement is executed and the process is repeated.
  • If the condition is evaluated to False, then the control comes out of the loop without executing the body of the loop. Later, the rest of the code is executed.

As long as condition is evaluated to True, the body of for loop and the updating statement are executed.
For example

for(i=1; i<=5;i++)
{
  printf(“%d”,i);
}
printf(“\nOut of the loop”);

In the above example,

  • For loop is executed for the first time and initialize the value of i =1.
  • Then, condition is checked and it is true since i = 1.
  • So, control enters into body of the loop and displays 1 on the screen using printf statement.
  • Then i is incremented by 1 and condition is checked again. The loop is repeatedly executed for i=1, 2, 3, 4 and 5, all these values are displayed one after other.
  • Finally, when i will be 6, the condition fails and control comes out of the loop and the message "Out of the loop" is displayed on the screen.

Here's an example to find sum of N natural numbers using For loop.

Algorithm:
Step1:    [Read the number of terms]
Read: N
Step2:    [Initialization]
    Sum = 0
Step3:    for i = 1 to N in steps of 1 do
    Sum = Sum + i
    [End of for]
Step4:    Write: Sum
Step5:    Exit

Looping Statements in Computer Programming, C Language


C program to find sum of natural number

main()
{
  int i,n,sum=0;
  printf("Enter the number of terms here:\n");
  scanf("%d",&n);
  for(i=1; i<=n; i++)
   {
     sum=sum+i;
   }
printf("The sun of n %d term = %d",n,sum);
getch();
}

Looping Statements in Computer Programming, C Language

Branching Statements in C

Comments

Popular posts from this blog

difference between structure and union in C Language

In c language article we will see the difference between union and structure. Both are the user define datatype in c language. See the table which is mentioned below: ASP.NET Video Tutorial Series Structure Union1.The keywordstruct is used to define a structure 1. The keyword union is used to define a union. 2. When a variable is associated with a structure, the compiler allocates the memory for each member. The size of structure is greater than or equal to the sum ofsizes of its members. The smaller members may end with unused slack bytes. 2. When a variable is associated with a union, thecompiler allocates thememory by considering the size of the largest memory. So, size of union is equal to the size of largest member. 3. Each member within a structure is assigned unique storage area of location. 3. Memory allocated is shared by individual members of union. 4. The address of each member will be in ascending order This indicates that memory for each member will start at different offset v…

Difference between Linear search and Binary Search in c language

SQL Video Channel : Download all SQL Video



Binary Search Linear Search Works only on sorted items. such as  1,2,3,4,5,6  etc
Works on sorted as well as unsorted items. 12,4,5,3,2,1 etc Very efficient if the items are sorted Very efficient if the items are less and present in the beginning of the list. such as Suppose your list items are : 12,3,4,5,1 and you want to search 12 number then you get beginning in the list. Works well with arrays and not on linked lists. Works with arrays and linked lists.
Number of comparisons are less More number of comparisons are required if the items are present in the later part of the array or its elements are more.

Memory representation of Linked List Data Structures in C Language

Memory representation of Linked List

             In memory the linked list is stored in scattered cells (locations).The memory for each node is allocated dynamically means as and when required. So the Linked List can increase as per the user wish and the size is not fixed, it can vary.

               Suppose first node of linked list is allocated with an address 1008. Its graphical representation looks like the figure shown below:


      Suppose next node is allocated at an address 506, so the list becomes,



  Suppose next node is allocated with an address with an address 10,s the list become,


The other way to represent the linked list is as shown below:




 In the above representation the data stored in the linked list is “INDIA”, the information part of each node contains one character. The external pointer root points to first node’s address 1005. The link part of the node containing information I contains 1007, the address of next node. The last node …