python基础之字符串索引与切片

字符串索引与切片：切片后组成新字符串与原字符串无关系增：str1+str2查：str1[index] str1[start_index:end_index]1，索引从0开始2，根据索引获取元素：索引超过字符串长度时报错s[0]--0标识索引值

s1 = 'python is good'
s2 = s1[0]
print(s2)

3，切片：顾头不顾尾-后面的数字表示的位数取不到
s[0:2]--0表示起始位置，2表示结束位置

 

s1 = 'python is good'
s2 = s1[0:2]
print(s2)

 

4，反向计数：s[-1]--取最后一位

s1 = 'python is good'
s2 = s1[-1]
print(s2)

 

s1 = 'python is good'
s2 = s1[-2:-1]
print(s2)

 

5，取所有元素：
s[0:]--最后一位不填写

s1 = 'python is good'
s2 = s1[0:]
print(s2)

 

6，等间隔取值：s[0:5:2]--0:5表示取值索引范围，2表示步长-间隔1位，间隔多少位

s1 = 'python is good'
s2 = s1[0:5:2]
print(s2)

s[5:0:-2]--同理，-2表示反向取值

s1 = 'python is good'
s2 = s1[5:0:-2]
print(s2)

 

s[5::-2]s[-1::-2]

s1 = 'python is good'
s2 = s1[-1::-2]
print(s2)

s[::-2]

来源：https://www.cnblogs.com/meifei/p/11378292.html