4.流程控制和循环
age = raw_input('age:')
if age>40:
print 'old!'
elif age>30:
print 'young!'
else:
print 'younger!'
if执行到情况匹配时就直接结束，并不是退出
else也可以省略
变量的声明等号 =
赋值的定义是双等号 ==
for循环
for * in * ：
5.while循环
while循环默认是死循环
for循环有起始结束，循环次数
print_num = input('which loop do you want it to be printed out?')
count = 0
while count < 100000:
if count == print_num:
print 'There you got the number:',count
choice = raw_input('Do you want to continue the loop?(y/n)')
if choice == 'n':
break
else:
while print_num <= count:
print_num = inout('Which loop do you want it to be printed out?')
print u"pass"
else:
print 'Loop:',count
count +=1
else:
print 'loop:',count