python入门 第5章 条件判断和循环

1、Python之if语句:
Python代码的缩进规则。具有相同缩进的代码被视为代码块，4个空格，不要使用Tab

age = 20if age >= 18:    print 'your age is', age    print 'adult'print 'END'

2、Python之if-else:

score = 55if score>=60:    print 'passed'else:    print 'failed'

3、Python之if-elif-else:

score = 85if score>=90:    print 'excellent'elif score>=80:    print 'good'elif score>=60:    print 'passed'else:    print 'failed'

4、Python之 for循环：

L = [75, 92, 59, 68]sum = 0.0for var in L:    sum=sum+varprint sum / 4

5、Python之 while循环：

sum = 0x = 1while x<100:    sum=sum+x    x=x+2print sum

6、Python之 break退出循环：

sum = 0x = 1n = 1while True:    sum=sum+x    x=x*2    n=n+1    if n>20:        breakprint sum

7、Python之 continue继续循环：

sum = 0x = 0while True:    x = x + 1    if x > 100:        break    if x%2==0:        continue    sum=sum+xprint sum

8、Python之 多重循环：

for x in [ 1,2,3,4,5,6,7,8,9 ]:    for y in [  0, 1,2,3,4,5,6,7,8,9 ]:       if x<y:           num=10*x+y;           print num