#第一部分 Python基础
>>>print 4
4
>>>type(“Hello World!”)
<type ‘str’>
>>>type(17)
<type ‘int’>
>>>type(3.2)
<type ‘float’>
and del from not while
as elif global or with
assert else if pass yield
break except import print
class exec in raise
continue finally is return
def for lambda try
>>>first=”100”
>>>second=”200”
>>>print first+second
100200
>>> input = raw_input()
Some silly stuff
>>> print input
Some silly stuff
#第二部分 条件执行
>>>17 and True
True
if x>0:
print ‘x is positive’
#使用if的时候需要注意:在if语句的后面必须要有冒号,在if的内含语句中,需要有缩进。
if x%2==0:
print ‘x is even’
else:
print ‘x is odd’
if x<y:
print ‘x is less than y’
elif x>y:
print ‘x is greater than y’
else:
print ‘x and y are equal’
if x=y:
print ‘x and y are equal’
else:
if x<y:
print ‘x is less than y’
else:
print ‘x is greater than y’
inp=raw_input(“Enter the number what you want:”)
try:
value=float(inp)
print value
except:
print “please enter a number!”
#第三部分 函数
>>> max('Hello world')
'w'
>>> min('Hello world')
' '
>>> len('Hello world')
11
#不必要的转换
>>> int('32')
32
#错误的示例
>>> int('Hello')
ValueError: invalid literal for int(): Hello
#从浮点到整型
>>> int(3.99999)
3
>>> int(-2.3)
-2
#从整型到浮点型
>>> float(32)
32.0
>>> float('3.14159')
3.14159
#从字符串(数字)到整型/浮点型
>>> str(32)
'32'
>>> str(3.14159)
'3.14159'
#通过import倒入模块random
#函数random会返回一个在0.0到1.0之间的数,包含0.0,却不包含1.0。
#range(10)表示从0-9循环
import random
for i in range(10):
x = random.random()
print x
#会得到类似以下的输出
0.301927091705
0.513787075867
0.319470430881
0.285145917252
0.839069045123
0.322027080731
0.550722110248
0.366591677812
0.396981483964
0.838116437404
#randint()函数会在指定的范围内返回一个整数。
>>> random.randint(5, 10)
5
>>> random.randint(5, 10)
9
#或者以这种形式进行
>>> t = [1, 2, 3]
>>> random.choice(t)
2
>>> random.choice(t)
3
#在使用时需要先写模块名,然后点出函数名。
>>> ratio = signal_power / noise_power
>>> decibels = 10 * math.log10(ratio)
>>> radians = 0.7
>>> height = math.sin(radians)
def print_lyrics():
print "I'm a lumberjack, and I'm okay."
print 'I sleep all night and I work all day.'
#第五部分 循环
n = 5
while n > 0:
print n
n = n-1
print 'Blastoff!'
while True:
line = raw_input('> ')
if line == 'done':
break
print line
print 'Done!'
while True:
line = raw_input('> ')
if line[0] == '#' :
continue
if line == 'done':
break
print line
print 'Done!'
friends = ['Joseph', 'Glenn', 'Sally']
for friend in friends:
print 'Happy New Year:', friend
print 'Done!'
#注意程序中使用print函数进行连接打印时,中间用逗号隔开。
largest = None
print 'Before:', largest
for itervar in [3, 41, 12, 9, 74, 15]:
if largest is None or itervar > largest :
largest = itervar
print 'Loop:', itervar, largest
print 'Largest:', largest
#程序的输出
Before: None
Loop: 3 3
Loop: 41 41
Loop: 12 41
Loop: 9 41
Loop: 74 74
Loop: 15 74
Largest: 74
#第六部分 字符串
#定义字符串
>>> fruit = 'banana'
#取字符串中的第二个字母
>>> letter = fruit[1]
>>> fruit = 'banana'
>>> len(fruit)
6
>>> length=len(fruit)
>>> last= fruit[length-1]
>>> s = 'Monty Python'
>>> print s[0:5]
Monty
>>> print s[6:13]
Python
>>> fruit = 'banana'
>>> fruit[:3]
'ban'
>>> fruit[3:]
'ana'
>>> greeting = 'Hello, world!'
>>> new_greeting = 'J' + greeting[1:]
>>> print new_greeting
Jello, world!
word = 'banana'
count = 0
for letter in word:
if letter == 'a':
count = count + 1
print count
>>> 'a' in 'banana'
True
>>> 'seed' in 'banana'
False
#两个字符串可以直接比较,例如
if word == 'banana':
print 'All right, bananas.'
#同样,可以使用大小于
if word < 'banana':
print 'Your word,' + word + ', comes before banana.'
elif word > 'banana':
print 'Your word,' + word + ', comes after banana.'
else:
print 'All right, bananas.'
>>> stuff = 'Hello world'
>>> type(stuff)
<type 'str'>
>>> dir(stuff)
['capitalize', 'center', 'count', 'decode', 'encode',
'endswith', 'expandtabs', 'find', 'format', 'index',
'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace',
'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip',
'partition', 'replace', 'rfind', 'rindex', 'rjust',
'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines',
'startswith', 'strip', 'swapcase', 'title', 'translate',
'upper', 'zfill']
>>> word = 'banana'
>>> index = word.find('a')
>>> print index
1
>>> line = ' Here we go '
>>> line.strip()
'Here we go'
>>> line = 'Please have a nice day'
>>> line.startswith('Please')
True
>>> line.startswith('p')
False
>>> line = 'Please have a nice day'
>>> line.startswith('p')
False
>>> line.lower()
'please have a nice day'
>>> line.lower().startswith('p')
True
>>> camels = 42
>>> 'I have spotted %d camels.' % camels
'I have spotted 42 camels.'
#第七部分 文件
>>> fhand = open('mbox.txt')
>>> print fhand
<open file 'mbox.txt', mode 'r' at 0x1005088b0>