Understanding of For loop

#include<stdio.h>
int main()
{
        int i;
        for(i=0;i<=5;i++)
              printf("Hello World");
         return 0;
}

Lets start with step by step and what will happen when condition is true:

Seq.No        Statement Flow                Explanation
01    Flow No 1 will be executed            i = 0
02    Flow No 2 will be executed            Condition Checking
03    Flow No 3 will be executed        True Condition and print Hello World
04    Flow No 4 will be executed              -
05    Flow No 5 will be executed            i = 1
06    Flow No 3 will be executed        True Condition and print Hello World
07    Flow No 4 will be executed              -
08    Flow No 5 will be executed            i = 2
09    Flow No 3 will be executed        True Condition and print Hello World
10    Flow No 4 will be executed              -
11    Flow No 5 will be executed            i = 3
12    Flow No 3 will be executed        True Condition and print Hello World
13    Flow No 4 will be executed              -
14    Flow No 5 will be executed            i = 4
15    Flow No 3 will be executed        True Condition and print Hello World
16    Flow No 4 will be executed              -
17    Flow No 5 will be executed            i = 5
18    Flow No 3 will be executed            False Condition

Therefore it gives five times Hello World . Ok Guys i think u will understand of whole scenario.

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For Loop in Java

The for loop is used to iterate the statement or a part of the program several times.
There are two forms of the for loop in java.
1. Traditional for loop
2. For-each loop

1. Traditional For Loop
Syntax of the traditional for loop is:

for(initialization ; condition ; increment/decrements)
{
       //statements
}

When the loop first starts , the initialization portion of the loop is executed.It is important to know that the initialization statement is only executed once.Next , condition is evaluated.This must be a Boolean expression.It checks the  loop control variable against a target value.If this expression is true , then the body of loop is executed otherwise terminates the loop.Next, the increment/decrements portion executed which is increments or decrements the loop control variable.
After first pass the loop iterates , first evaluated the conditional statements ,then executing the body of loop and then executes the increments/decrements portion.This process repeats until the condition false.


Flow Chart Of  Traditional For Loop:

Simple program of traditional for loop:

package org.modi;
public class Test
{
	public static void main(String[] args)
	{
		for(int i=0;i<5;i++)
		{
			System.out.println("loop body " + i );
		}
	}
}

OUTPUT

loop body 0
loop body 1
loop body 2
loop body 3
loop body 4

2. For-each Loop

The for-each loop was introduce in JDK 5(1.5)  version of java.The for-each loop is also know as enhanced for loop.The for-each specially designed for iterate the collection of objects , such as an array.It iterate all the elements from starting element to last element.We can con control the number of iteration it iterate all the elements one by one.

Syntax of for-each loop:

for(type variable : collection)
{
   //statements
}

Here, type specifies the type (e.g. String , int ) and variable specifies the name of the iteration variable that will receive the elements form the collection , one at a time from begin to end.The collection is the collection of elements which will be iterated by the loop.

Simple program of the for-each loop:

package org.modi;
public class Test
{
   public static void main(String[] args)
   {
	int[] arr={0,1,3,4};
	for(int itr : arr)
	{
	   System.out.println("loop body " + itr);
	}
    }
}

OUTPUT

loop body 0
loop body 1
loop body 3
loop body 4

Some Important points:

1. If for loop body contains only one statement then , no need for curly braces.
E.g.
for(int i=0 ; i< 5 ; i++)
      System.out.println("Hello World!");
2. If we declare a variable inside for loop , then the scope of the variable ends with ends of for loop.
3. To create infinite loop leave all the parts of for loop empty.
E.g.
for(  ;   ;  )

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