Learning with python: Chapter3~4 Functions,Conditionals and Recursion
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 "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 than2
3 is greater than1
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
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