python——语句

条件语句

if condition:    #code list[elif condition_1:    #code list]...[elif condition_n:    #code list][else:    #code list]

注1：[]表示optional

注2：elif不能拆分为else if

注3：不支持switch

score = 90if score >= 90:    print 'excellent'score = 80if score >= 60:    print 'pass'else:    print 'fail'score = 70if score >= 90:    print 'A'elif score >= 80:    print 'B'elif score >= 70:    print 'C'elif score >= 60:    print 'D'else:    print 'E'

循环语句

for...in

sum = 0for i in range(11):    sum = sum + iprint sum

while

i = 0sum = 0while i < 11:    sum = sum + i    i = i + 1print sum

注：不支持do while

空语句

pass

条件语句

salary = 15000if salary >= 30000:    print 'very high income'elif salary >= 20000:    print 'high income'elif salary >= 10000:    print 'middle income'else:    print 'low income'

注意：

• elif意义是else if，但不能写成else if
• elif分支optional
• else分支optional

def judgeCondition(x):    if x:        print True    else:        print Falsex = 0judgeCondition(x)x = 1judgeCondition(x)x = ''judgeCondition(x)x = "abc"judgeCondition(x)x = ()judgeCondition(x)x = (1, 2)judgeCondition(x)x = NonejudgeCondition(x)

output：

FalseTrueFalseTrueFalseTrueFalse

单独变量作为判断条件时，有以下情况：

• 整型&浮点型：0为False，非0为True
• 字符串：空串为False，非空串为True
• list&tuple&dict&set：空为False，非空为True

循环语句

for...in

namelist = ['tom', 'jack', 'martin']for name in namelist:    print name

while

namelist = ['tom', 'jack', 'martin']index = 0while index < len(namelist):    print namelist[index]    index = index + 1