Python快速上手之流程控制語法(day2)

2021-10-03 07:39:50 字數 2242 閱讀 3397

python流程控制語法

if語句

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的條件可以是數字或字串或者布林值true和false(布林表示式)

#如果是數字,則只要不等於0,就為true

#如果是字串,則只要不是空串,就為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!"

巢狀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迴圈

count = 0

while count < 5:

print count, " is less than 5"

count = count + 1

else:

print count, " is not less than 5"

x=2i=0

while x<34:

i+=1

if i==12:

print "break....................................."

break

; print x

x=35

i=0while x<34:

i+=1

if i==12:

print "break....................................."

break

; print x

else:

print "沒有執行迴圈......."

for迴圈

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;

#遍歷集合

r=range(10,20)

r=#set型別r=[

"aaa",3,"c"

]print(r)

for num in r:

print(num)

r=print(r)

for num in r.values(

): print(num)

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