Funny Sayings Restraunts

013) The global variables

As we have studied, when you create functions state variables (known as local variables) they are all 'inside the function block with instead declare global variables that can be used in all the functions. Some examples:

EXAMPLE OF ERROR NOT GLOBAL VARIABLE:

 
   final  calcoloeta  ()  :   
   year = 2008   
  tuoanno  =   input   ( "In what year were you born : )   
  age  =  years  -  tuoanno    
         print     "  Hai  ",  eta  ,"  anni  "     
   calcoloeta  ()     
     print     "  Siamo nell' anno  ",   anno   #si richiama la variabile 
                               #anno     

Output:

  
   In che anno sei nato: 1985   
   Hai 23 anni   
   Siamo nell' anno   
   Traceback (most recent call last):   
     File "prova.py", line 25, in        
       print "We're in 'year', year  
  NameError: name 'year' is not defined  
 

What's happening? The interpreter returns error because the line print "We're in 'year," year we try to recall the year that variable within the function as a local variable is then valid only inside the function the problem can be solved by declaring years as a global variable:

 
   final  calcoloeta  ()  :   
   global  years  year # becomes a global variable   
  years   = 2008  
  tuoanno  =     input ("What year were you born : )   
  age  =  years  -  tuoanno  
     print" You   "  age, " years "   
  calcoloeta  ()   
  print   "We are in   '  years,   years   # # relies on the variable 
 years  

In this case there should be no mistakes because years although a variable within a function and "uttilizzabile all" thanks to global.