PythonStudy——字符串常用操作 String common operations

# 1.字符串的索引取值: 字符串[index]
# 正向取值从0编号，反向取值从-1编号

s1 = '123abc呵呵'
print(id(s1))  #
print(s1[0], id(s1[0]))  #
t_s = ''
print(id(t_s))  #

# 取出c

print(s1[5], s1[-3])

# 2.字符串拼接

s2 = '你好'
s22 = '帅'
ss2 = s2 + s22
print(ss2, id(s2), id(s22), id(ss2))

# 如果要拼接其他类型

a = 10
b = ""
c = True
# res = "1020True"
res = "%s%s%s" % (a, b, c)  # 方法1
print(res)
res = str(a) + b + str(c)  # 方法2
print(res)

# 3.字符串长度

s3 = ''
ln1 = s3.__len__()
print(ln1)
ln2 = len(s3)
print(ln2)

# 4.字符串切片: 取子字符串 - [::] - [start_index:end_index:step]

s4 = '123abc呵呵'
sub_s = s4[0:6:]
print(sub_s)  # 123abc
sub_s = s4[0:6:2]
print(sub_s)  # 13b
sub_s = s4[::-1]
print(sub_s)  # 呵呵cba321
sub_s = s4[-1:-6:-1]
print(sub_s)  # 呵呵cba

# 5.成员运算：判断某字符串是否在该字符串中

s5 = '123abc呵呵'
ss5 = '12a'
print(ss5 in s5)  # False
print(ss5 not in s5)  # True

# 6.字符串循环(遍历)

s6 = '123abc呵呵'
for v in s5:
    print(v)