python学习笔记二：流程控制_python

概述一、if else：#!/usr/bin/pythonx = int(raw_input('please input:'))if x >= 90:if x >= 95:print 'a+'else:print 'a'elif x >= 80:if x >= 85:print 'b+'else:print 'b'elif x >= 70:if x >= 75:print 'c+'else:print 'c'else:if x >= 60:print 'd+'else:print 'bad'二、逻辑运算符 and or not#!/usr/bin/pythonx = int(raw_input('please input x:'))y = int(raw_input('please input y:'))if x >= 90 and y >= 90:print 'a'elif x >= 80 or y >= 80:print 'b'elif not x < 60 and (not y < 60):print 'c'else:print 'bad'三、for序列：#!/usr/bin/pythons = "hello python"for x in s:print xfor index in range(len(s)):print s[index]字典：#!/usr/bin/pythondic = {'a':1,'b':2,'c':3}for x in dic:print x,dic[x]for k,v in dic.items():print k,v控制else：for正常执行完会执行else中的内容，否则不会（如下面的代码执行过程按Ctrl+c）#!/usr/bin/pythonimport timefor x in range(10):print xtime.sleep(1)else:print 'end'break：跳出当前这层循环#!/usr/bin/pythonfor x in range(10):print xif x == 6:breakelse:print 'end'这里不会执行else中的内容pass：占位exit：退出#!/usr/bin/pythonfor x in range(10):print xif x == 2:print 'hello',xcontinueif x == 4:passif x == 5:exit()if x == 6:breakprint '*'*10else:print 'end'四、while 当条件失败，正常结束会执行，执行break后else中不执行#!/usr/bin/pythonx = 'hello'while x != "q":print xx = raw_input('please input something,q for quit:')if not x:breakelse:print 'ending' 一、if else：x = int(raw_@R_404_5983@(if x >= 90:
if x >= 95:
print 'a+'
else:
print 'a'
elif x >= 80:
if x >= 85:
print 'b+'
else:
print 'b'
elif x >= 70:
if x >= 75:
print 'c+'
else:
print 'c'
else:
if x >= 60:
print 'd+'
else:
print 'bad'

x = int(raw_@R_404_5983@(= int(raw_@R_404_5983@(if x >= 90 and y >= 90:
print 'a'
elif x >= 80 or y >= 80:
print 'b'
elif not x < 60 and (not y < 60):
print 'c'
else:
print 'bad'

for x in s:
print x

for index in range(len(s)):
print s[index]

字典：

= {:1,:2,:3for x in dic:
print x,dic[x]

for k,v in dic.items():
print k,v

控制

else：for正常执行完会执行else中的内容，否则不会（如下面的代码执行过程按Ctrl+c）

for x in range(10):
print x
time.sleep(1)
else:
print 'end'

break：跳出当前这层循环

x range(10 x == 6

这里不会执行else中的内容

pass：占位