wordpress - Fixing the width and height of the post thumbnail -

I'm having trouble determining the width and height of my post thumbnail I

here's the image There is a link for

As you can see that both posts have different dimensions

I have tried to fix the height and width of my post. Sometime in Actually what I want to achieve is that if I can not upload an image on the image image, then it will come out with a height of 250 pixels and a width of 250 pixels. But whatever I do is wrong.

This is the code I have encoded

index.php

  & lt? Php if (has_post_thumbnail) ()) {The_post_thumbnail (); }? & Gt;   
 function.php  
 // post thumbnail support3  
  add_theme_support ('post thumbnail', array ('post') ); Set_post_thumbnail_size (250, 250);   
 Am I missing something? I'm still trying to code in wordpress and php language Actually I am still a newbie. I really want to complete this without having to do this on the plug   
 
 after "text" itemprop = "text" > 
 Here is the code:  
  & lt ;? Php the_post_thumbnail (array (215152), array ('class' = & gt; 'thumbnail')); ? & Gt;   
 array (215152) You can change your value for your price which is the height and width  
 or  
 you can use used images  
  & lt ;? php if (has_post_thumbnail ()) {$ large_image_url = wp_get_attachment_image_src (get_post_thumbnail_id (), 'large'); echo '& lt; img src = ''. $ Large_image_url [0] '' title = "'the_title_attribute (' echo = 0 ')' 'width =" 250px "height =" 250px "> gt;' ...} & gt;