Python控制结构

Python控制结构

1. Python控制结构简介

2. 定义函数

<1>. Python控制结构

1.1 if

print("#############if statement###############");
x = int(input("Enter an integer :"));
if x < 0 :
x = 0;
print("Negative changed to zero .");
elif x == 0 :
print("Zero");
elif x == 1 :
print("Single");
else :
print("None");

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1.2 for

############################for statement
print("#############for statement###############");
a = ['cat', 'window', 'defenestrate'];
for x in a :
print(x, len(x));
print("#############range function###############");
for i in range(5) :
print(i);
a = ['Mary', 'had', 'a', 'little', 'lamb'];
for i in range(len(a)) :
print(i, a[i]);

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1.3 break and continue

print("#############break and continue###############");
for n in range(2, 10) : # 2 - 9
for x in range(2, n):
if n % x == 0 :
print(n, 'equals', x, '+', n // x);
break;
else :
print(n);

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1.4 pass

# ########################pass action test ##############
if False :
pass; ''' do nothing '''

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<2>. 定义函数 2.1 定义函数基础

# define the function
def fib(n):
# print the Fibonacci series up to n.
a, b = 0, 1;
while a < n :
print a;
a, b = b, a +b;

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2.2 函数默认参数

'''
default arguments
'''
def ask_ok(prompt, retries = 4, complaint = 'Yes or no, please') :
while True:
ok = raw_input(prompt);
if ok in ['y', 'Y', 'yes'] :
return True;
if ok in ['n', 'no', 'nop'] :
return False;
retries = retries - 1;
if retries < 0:
raise IOError('refusenik user');
print complaint;

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2.3 不定参数

'''
Arbitrary arguments function
'''
def arbitraryArgsFunc(arg1, *args):
# just print the arbitrary arguments
for i in range(0, len(args)):
print(args[i]);
arbitraryArgsFunc('arg1', 'arg2', 'arg3');

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2.4 Lambda表达式

'''
lamba function, just like the function template
'''
def make_incrementor(n):
return lambda x:x + n;
f = f = make_incrementor(42);
print(f(0));

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作者: 三里屯摇滚发布时间: 2011-06-10

python 的语法真是优雅。

作者: coolesting 发布时间: 2011-06-13