一文详细说说Python中常用的字符串和数组方法(面试官常问)

s = "hello python"
res = s.upper()
print(res)  # 输出：HELLO PYTHON

s = "HELLO PYTHON"
res = s.lower()
print(res)  # 输出：hello python

s = "hello python"
res = s.title()
print(res)  # 输出：Hello Python

s1 = "12345"
s2 = "123a"
print(s1.isdigit())  # True
print(s2.isdigit())  # False

s1 = "abc"
s2 = "abc1"
print(s1.isalpha())  # True
print(s2.isalpha())  # False

s = "python.txt"
print(s.startswith("py"))   # True
print(s.startswith("txt"))  # False

s = "python.txt"
print(s.endswith(".txt"))  # True
print(s.endswith(".jpg"))  # False

s = "abcdef"
print(s.find("c"))   # 2
print(s.find("z"))   # -1

s = "abcdef"
print(s.index("d"))  # 3
# print(s.index("z"))  # 报错

s = "aabbaacc"
print(s.count("a"))  # 4
print(s.count("b"))  # 2

s = "1,2,3,4"
lst = s.split(",")
print(lst)  # ['1', '2', '3', '4']

lst = ["1","2","3"]
s = "-".join(lst)
print(s)  # 1-2-3

s = "hello world"
res = s.replace("world","python")
print(res)  # hello python

s = "  python  "
res = s.strip()
print(res)  # python

# 定义测试字符串
s = "ABCDEFG"
# 正向索引：0 1 2 3 4 5 6
# 反向索引：-7 -6 -5 -4 -3 -2 -1

# 1. 基础切片 [start:end]
print("1. 基础切片[1:4]:", s[1:4])   # BCD

# 2. 从开头截取到指定位置 [:end]
print("2. 开头到索引3:", s[:3])    # ABC
print(s[:-1]) # 这个代表去掉最后一个字符，取前面所有字符。 也就是 # ABCDEF

# 3. 从指定位置截取到末尾 [start:]
print("3. 索引2到末尾:", s[2:])    # CDEFG

# 4. 复制整个字符串 [:]
print("4. 完整复制字符串:", s[:])     # ABCDEFG

# 5. 指定步长截取 [start:end:step]
print("5. 步长为1全取:", s[0:7:1]) # ABCDEFG
print("5. 步长为2隔位取:", s[::2])   # ACEG

# 6. 负数索引（从右计数）
print("6. 最后1个字符:", s[-1])    # G
print("6. 倒数第3到倒数第1:", s[-3:-1]) # EF

# 7. 负步长：反转字符串
print("7. 整体反转字符串:", s[::-1])  # GFEDCBA

# 8. 倒序区间截取
print("8. 倒序区间截取[5:0:-1]:", s[5:0:-1])  # FEDCB

# 9. 跳过前N个字符
print("9. 跳过前3个字符:", s[3:])    # DEFG

# 10. 截取最后N个字符
print("10. 截取最后3个字符:", s[-3:])   # EFG

lst = [1,2,3]
lst.append(4)
print(lst)  # [1, 2, 3, 4]

lst = [1,3,4]
lst.insert(1,2)
print(lst)  # [1, 2, 3, 4]

lst1 = [1,2]
lst2 = [3,4]
lst1.extend(lst2)
print(lst1)  # [1, 2, 3, 4]

lst = [1,2,3]
num = lst.pop(1)
print(num)   # 2
print(lst)   # [1, 3]

lst = [1,2,1,3]
lst.remove(1)
print(lst)  # [2, 1, 3]

lst = [1,2,3]
lst.clear()
print(lst)  # []

lst = [2,5,8]
print(lst.index(5))  # 1

lst = [1,1,2,2,2]
print(lst.count(2))  # 3

lst = [5,2,9,1]
lst.sort()
print(lst)  # [1, 2, 5, 9]

lst = [1,2,3,4]
lst.reverse()
print(lst)  # [4, 3, 2, 1]

lst = [10,20,30,40,50]
print(lst[2:4])   # [30, 40]
print(lst[::-1])  # [50, 40, 30, 20, 10]

s = "python"
lst = [1,2,3]
print(len(s))   # 6
print(len(lst)) # 3

print("py" in "python")  # True
print(2 in [1,2,3])      # True

print("a"+"b")    # ab
print([1]+[2,3])  # [1, 2, 3]