Learning with python: Chapter3~4 Functions,Conditionals and Recursion

sunyke

　　

　　1. Call Functions


>>> betty=type("32") # call function @type

>>> print betty

<type 'str'>
>>> id(betty) # call function @id

56091456
>>> betty=3

>>> id(betty)

155577720
>>> int("32") # call function @int

32
>>> int(3.99)

3
>>> int(-2.3)

-2
>>> float(32)

32.0
>>> float("3.1415926")

3.1415926000000001
>>> str(3.1415926) # call function @str

'3.1415926'
>>> minute=58

>>> float(minute)/60

0.96666666666666667
>>> import math # use math functions, should import math

>>> decibel=math.log10(17.0)

>>> decibel

1.2304489213782739
>>> angle=1.5

>>> height=math.sin(angle)

>>> height

0.99749498660405445
>>> degrees=45

>>> angle=degrees*2*math.pi/360.0

>>> math.sin(angle)

0.70710678118654746
>>> math.sqrt(2)/2.0

0.70710678118654757
>>> x=math.exp(math.log(10.0))

>>> x

10.000000000000002
　　

　　2.Define Functions
　　The syntax for a function definition is


def NAME( LIST OF PARAMETERS ):
STATEMENTS

　　Examples：
　　

# define functions
print "===========def func==========="
def newLine():  # def func
print
print "First Line."
newLine();
print "Second Line"
newLine();
def odd_even(x):
if x%2==0:
print x, "is even"
else:
print x, "is odd"
odd_even(10);
odd_even(11);

def comp(x,y):
if x < y:  
print x, "is less than ",y   # incdent 2 space is OK, not must TAB
elif x > y:
print x, "is greater than ",y
else:
print x, "and", y, "are equal"
comp(1,2);
comp(3,1);
comp(1,1);
x = -100;
if 0 < x < 200:
print "x is between 0~200"
else:
print "x is not in scale"
# recursion
def countdown(n):
if n == 0:
print "Blastoff!"
else:
print n
countdown(n-1)
countdown(5);
# keyboard input
print "===========input==========="
# print "Please input:"
inputthing = raw_input("What is your name?");
print inputthing
speed=input("What is the train speed?");  # integer
print speed
　　Results：
　　

===========def func===========
First Line.
Second Line
10 is even
11 is odd
1 is less than  2
3 is greater than  1
1 and 1 are equal
x is not in scale
5
4
3
2
1
Blastoff!
===========input===========
What is your name?xiahouzuoxin
xiahouzuoxin
What is the train speed?100
100