Python控制结构

st0627

　　

　　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");
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);
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);
1.4 pass
# ########################pass action test ##############
if False :
pass;  ''' do nothing '''


<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;
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;
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);
   

　　arbitraryArgsFunc('arg1', 'arg2', 'arg3');
2.4Lambda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));