对python中的控制条件、循环和跳出详解

a=100

if a > 80 :

print a,">80"

else :

print a,"<80"

 

a=60

if a < 50 :

print a,"<50"

elif a > 50 and a < 80 :

print a,">50 and ",a,"<80"

else :

print a,">80"

 

a = [] # 0 "" None []

if a:

  print "a is true"

else:

  print "a is false"

#while for rnage()

a=10

while a<20:

  print a

  a += 1

# while True: #死循环

#   print "aaa"

 

a=[1,2,3,4,5,6]

for i in a : #不能写死循环

  print i

 

print range(1,10) #默认步长为为1,不能是小数

print range(1,10,2)

#continue break

a=range(1,10)

for i in a:

  if i%4==0 :

    #continue

    break

  else :

    print i

else :

  print "final out is ok"