What is difference between For and foreach loop??

In addition to everything that has already been said, perhaps it would help to add that foreach is usuallly more convenient because it gives you an object that you can use in your code and that is a little easier to work with. It is a slight convenience for you. It might be less efficient for the computer but your efficiency is important too.

Also, you can think of a for loop as a while loop with a couple of extra lines. For example:

for (int i=0; i< 9; ++i)
;

Is the same as or nearly the same as:

int i = 0;
while (i<9)
        ++i;

What Dorababu said is true.

In addition, foreach is only good for looping through items in a collection.  The for command is used for other things as well.  For example, if you just want to perform an action a specific number of times you would do this:

for (int x = 0; x < 10;  x++) 


For also allows a lot more control.  Here I'm looping from 0 to somevalue in 5 unit increments:

for (int x = 0;  x < someValue;  x += 5)


Here I'm looping from 300 until x < the value of Foo( ).  Foo( ) is recalculated after each loop.  I reduce x by .3 after each loop.  You can't do that kind of thing with a foreach loop.  A foreach loop is meant to perform some action for each item in a collection.

for(int x = 300;  x < Foo( );  x *= .7)


As far as looping through each item in a collection, you can use for or foreach.  Either one is fine.

foreach is using IEnumerable to loop through collection. This makes it impossible to modify this collection(remove, add items), but you still can modify objects inside, if they are reference types.

for is simple combination of simple loop combined with direct access to items in collection. There is no kind of blocking while this loop is going.