Python流程控制语法
if语句
var1 = 100
if var1:
print "1 - Got a true expression value"
print var1
var2 = 0
if var2:
print "2 - Got a true expression value"
print var2
print "Good bye!"
#if的条件可以是数字或字符串或者布尔值True和False(布尔表达式)
#如果是数字,则只要不等于0,就为true
#如果是字符串,则只要不是空串,就为true
if else
var = 100
if var == 200:
print "1 - Got a true expression value"
print var
elif var == 150:
print "2 - Got a true expression value"
print var
elif var == 100:
print "3 - Got a true expression value"
print var
else:
print "4 - Got a false expression value"
print var
print "Good bye!"
嵌套if else
var = 100
if var < 200:
print "Expression value is less than 200"
if var == 150:
print "Which is 150"
elif var == 100:
print "Which is 100"
elif var == 50:
print "Which is 50"
elif var < 50:
print "Expression value is less than 50"
else:
print "Could not find true expression"
print "Good bye!"
while循环
count = 0
while count < 5:
print count, " is less than 5"
count = count + 1
else:
print count, " is not less than 5"
x=2
i=0
while x<34:
i+=1
if i==12:
print "break....................................."
break;
print x
x=35
i=0
while x<34:
i+=1
if i==12:
print "break....................................."
break;
print x
else:
print "没有执行循环......."
for循环
for i in range(0,5):
print i;
for i in range(0,5,1):
print i;
for i in range(5,0,-1):
print i;
#遍历集合
r=range(10,20)
r={1,2,3,4,5} #set类型
r=["aaa",3,"c"]
print(r)
for num in r:
print(num)
r={"a":9,"b":10}
print(r)
for num in r.values():
print(num)