Python学习笔记03

 

区间访问：[from:to:step]

1. step默认是1；from表示起始索引（包括）,to表示结束索引（不包括）
2. step如果有符号，表示方向从右到左;
3. from，to有符号，表示从倒数开始算，如-3表示倒数第三个
4. string是特殊的类型，且是元组，不能修改；
5. 对list添加元素，不能像JS一样，要使用append(item)函数

 

# [from:to:step] from include，to not include,step default is 1. ( Nagetive sign refer than the direction is from right to left.)   s1 = (2, 1.3, 'love', 5.6, 9, 12, False) s2 = [True, 5, 'smile']   print s1==s1[:] #default is the list print s1[:5] # 前5个 print s1[2:] # 从第3开始   print s1[0:5:2] #每两个   print s1[2:0:-1] # not include s1[0] ,because 0 is the TO.     # 倒序引用   print s2[-1] print s2[1] == s2[-2]   # String is a tuple ,can't modify the char. str = 'abcdef' print str[2:4],type(str) #str[0] = 'z' will throw   # 添加元素,需要调用 append s2.append('pzdndd') print s2[-1] == 'pzdndd'

 

数学 +, -, *, /, **, %

判断 ==, !=, >, >=, <, <=, in

逻辑 and, or, not

print 3**4 # 乘方 81   print 5 in [1,3,5] #   print True and False print True or False print not True