User Defined Functions in PHP

1
User Defined Functions in PHP

• why do you need functions/subroutines?
• modular codes, nice programming practice
• pass parameters and get values
• avoid repeating certain lines again and again

2
User Defined Functions in PHP

• lt?php function say_hi() print "Hi
  there!"
• say_hi()
• echo I will say Hi again
• say_hi()
• ?gt

3
User Defined Functions in PHP

• Returning values from a function
• lt?php function say_hi() return "Hi
  there!"var say_hi() print var
  print say_hi()?gt

4
User Defined Functions in PHP

• Function Arguments
• lt?php function say_hi(name) return "Hi
  there name!"
• print say_hi("Billy Joe Bob")
• ?gt

5
User Defined Functions in PHP

• lt?php function say_hi(name, greeting)   
   return "greeting name!"print
  say_hi("Billy Joe Bob", "Hi there") ?gt

6
User Defined Functions in PHP

• Scope of variables?
• where in a script a variable can be used
• variables are available in whole script except
  functions
• you have to pass parameters to functions
• variables inside functions cant be used outside

7
Global and Local variables

• Global Variables
• Declared/defined in the main script
• Have a larger scope
• Local Variables
• Declared/defined in functions
• Have a smaller scope

8
User Defined Functions in PHP

• lt?php x 1function add()   x10   
• xadd()print x?gt

9
User Defined Functions in PHP

• lt?php x 1function add()
     GLOBALS"x"add() print x?gt

10
User Defined Functions in PHP

• lt?php
• link mysql_connect("localhost", "ist210",
  "ist210")
• db "ist210" table_name "gymnasts"
• mysql_select_db(db, link)
• result mysql_query("select from
  gymnasts")
• display_records(result)
• mysql_close(link)
• function display_records(records)
• while(one_record mysql_fetch_row(records
  ))
• foreach (one_record as field)
• print "field "
• print "ltbrgt"
• ?gt

11
User Defined Functions in PHP

• function display_records(records)
• print "lttable width200 border1gt\n"
• while(one_record mysql_fetch_row(records)
  )
• print lttrgt\n
• foreach (one_record as field)
• print "\tlttdgtfieldlt/tdgt\n"
• print "lttrgt\n"
• print "lt/tablegt\n"

12
Including files

• lt?php
• //Global variables
• include("filename.php")
• //here comes the code for this file
• ?gt
• Global variables can be used inside included
  files!!!!!