In [ ]:

    

# function
# A function is a block of code which can be called n number of times.
#


    

In [1]:

    

# function start with a 'def' keyword
# function returns a value
# Your function return a None if there is no value to return.if not it returns a value.
def my_func():
    print "hello!! world"


    

In [4]:

    

print my_func,type(my_func)
print my_func()
my_func


    

    




<function my_func at 0x7f5bac115f50> <type 'function'>
hello!! world
None






    
Out[4]:





<function __main__.my_func>

In [5]:

    

# return is not a print value.
# return marks the end of the function.
def my_func():
    return "hello!!! world"


    

In [6]:

    

print my_func()


    

    




hello!!! world

In [7]:

    

# return marks the end of the function.
# how many return values can we have in a function ? n number provided we have conditions.
def my_func():
    return "hello!!! world"
    print "line1"
    print "line2"
    print "line3"


    

In [8]:

    

print my_func()


    

    




hello!!! world

In [9]:

    

def my_func():
    print "line1"
    print "line2"
    print "line3"
    return "hello!!! world"


    

In [10]:

    

print my_func()


    

    




line1
line2
line3
hello!!! world

In [14]:

    

# namespaces or local and global variables
# Any value you define within a function is restricted to the local namespace.
# there is no syntax which can get that value for you.
# locals() - inbuild function.
# value x is only available during the runtime of the function.
def my_func():
    x = 10
    print locals()
    return x


    

In [15]:

    

print my_func() # 10


    

    




{'x': 10}
10

In [13]:

    

print x # None,x,10,error


    

    




---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-13-9e0b17f1da3b> in <module>()
----> 1 print x # None,x,10,error

NameError: name 'x' is not defined

In [ ]:

    

# global variables
#  If you local variables are not there your function looks into the global namespaces.

In [1]: y = 10

In [2]: def my_func():
   ...:     print locals()
   ...:     return y
   ...: 

In [3]: print my_func() # 10
{}
10

In [5]: globals()
Out[5]: 
{'In': ['',
  u'y = 10',
  u'def my_func():\n    print locals()\n    return y',
  u'print my_func() # 10',
  u'print globals()',
  u'globals()'],
 'Out': {},
 '_': '',
 '__': '',
 '___': '',
 '__builtin__': <module '__builtin__' (built-in)>,
 '__builtins__': <module '__builtin__' (built-in)>,
 '__doc__': 'Automatically created module for IPython interactive environment',
 '__name__': '__main__',
 '_dh': [u'/home/khyaathi/Documents/git_repos/python-batches/batch-65'],
 '_i': u'print globals()',
 '_i1': u'y = 10',
 '_i2': u'def my_func():\n    print locals()\n    return y',
 '_i3': u'print my_func() # 10',
 '_i4': u'print globals()',
 '_i5': u'globals()',
 '_ih': ['',
  u'y = 10',
  u'def my_func():\n    print locals()\n    return y',
  u'print my_func() # 10',
  u'print globals()',
  u'globals()'],
 '_ii': u'print my_func() # 10',
 '_iii': u'def my_func():\n    print locals()\n    return y',
 '_oh': {},
 '_sh': <module 'IPython.core.shadowns' from '/usr/lib/python2.7/dist-packages/IPython/core/shadowns.pyc'>,
 'exit': <IPython.core.autocall.ExitAutocall at 0x7fe679b02550>,
 'get_ipython': <bound method TerminalInteractiveShell.get_ipython of <IPython.terminal.interactiveshell.TerminalInteractiveShell object at 0x7fe67a449a10>>,
 'my_func': <function __main__.my_func>,
 'quit': <IPython.core.autocall.ExitAutocall at 0x7fe679b02550>,
 'y': 10}


    

In [16]:

    

# local variables are given higher priority then global variable.
y = 10
def my_func():
    y = 2
    print locals()
    return y

print my_func() # 2,2 
print y # (2,10),10


    

    




{'y': 2}
2
10

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# global keyword


    

In [17]:

    

balance = 0

def deposit():
    balance = balance + 5000
    return balance

def withdraw():
    balance = balance - 1000
    return balance


    

In [18]:

    

print deposit()


    

    




---------------------------------------------------------------------------
UnboundLocalError                         Traceback (most recent call last)
<ipython-input-18-f63fab9016ab> in <module>()
----> 1 print deposit()

<ipython-input-17-a75502b6cdfa> in deposit()
      2 
      3 def deposit():
----> 4     balance = balance + 5000
      5     return balance
      6 

UnboundLocalError: local variable 'balance' referenced before assignment

In [19]:

    

# one of crazy solution

def deposit():
    balance = 0
    balance = balance + 5000
    return balance

def withdraw():
    balance=0
    balance = balance - 1000
    return balance


    

In [20]:

    

# srikant
# imps
print deposit() # 5000


    

    




5000

In [21]:

    

print withdraw()


    

    




-1000

In [41]:

    

# exact solution

balance=0

def deposit():
    global balance
    print locals()
    balance = balance + 5000
    return balance

def withdraw():
    global balance
    print locals()
    balance = balance - 1000
    return balance


    

In [42]:

    

# srikant
# imps
print deposit() # 5000


    

    




{}
5000

In [43]:

    

print withdraw()


    

    




{}
4000

In [44]:

    

# pulling balance from global namespace
print globals()['balance']


    

    




4000

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