php - Incrementing a string producing unexpected results -

I was just playing with PHP, can someone tell me why the code below given 5566 instead of 6666 print Does it?

  $ a = 5; $ B = $ A; All alo $ a ++ $ B ++; Echo "\ n"; All alo $ a ++ $ B ++;   
 Does it resonate $ 1 and add 1 to it? Why this result does not resonate?  
 Edit: Another simple example to look at:  
  $ a = 5; $ B = $ A ++; All alo $ a ++ $ b;   
 output  65    
 
 
 this When you put  ++  after (suffix), it should be done after increments  
  55 66   
 The statement is executed. If you want  
  66 66   
 then do  
  $ a = 5; $ B = $ A; Resonance ++ $ a ++ $ b; Echo "\ n"; All alo $ a ++ $ B ++;