Python判断字符串是否包含特定子串的7种方法

>>> "llo" in "hello, python"
True
>>>
>>> "lol" in "hello, python"
False

>>> "hello, python".find("llo") != -1
True
>>> "hello, python".find("lol") != -1
False
>>

def is_in(full_str, sub_str):
    try:
        full_str.index(sub_str)
        return True
    except ValueError:
        return False

print(is_in("hello, python", "llo"))  # True
print(is_in("hello, python", "lol"))  # False

def is_in(full_str, sub_str):
    return full_str.count(sub_str) > 0

print(is_in("hello, python", "llo"))  # True
print(is_in("hello, python", "lol"))  # False

>>> "hello, python".__contains__("llo")
True
>>>
>>> "hello, python".__contains__("lol")
False
>>>

>>> import operator
>>>
>>> operator.contains("hello, python", "llo")
True
>>> operator.contains("hello, python", "lol")
False
>>> 

import re

def is_in(full_str, sub_str):
    if re.findall(sub_str, full_str):
        return True
    else:
        return False

print(is_in("hello, python", "llo"))  # True
print(is_in("hello, python", "lol"))  # False

sample_str = "Hello, World! This is a sample string with安hjj in it."

# 单字符访问
print("第一个字符:", sample_str[0])  # 输出: H
print("第五个字符:", sample_str[4])  # 输出: o

# 子串切片（左闭右开）
print("前5个字符:", sample_str[:5])  # 输出: Hello
print("第7到12个字符:", sample_str[7:12])  # 输出: World

target = "安hjj"
index = sample_str.find(target)
if index != -1:
    print(f"找到'{target}'，位置在:{index}")
    print("完整子串:", sample_str[index:index+len(target)])
else:
    print(f"未找到'{target}'")

import re

# 匹配'安'开头后跟3个任意字符
pattern = re.compile(r'安\w{3}')  
match = pattern.search(sample_str)
if match:
    print("正则匹配结果:", match.group())

# filename="string_operations.py"
def main():
    sample_str = "Hello, World! This is a sample string with安hjj in it."
    
    # 基础访问
    print("索引访问示例:")
    print("第2字符:", sample_str[1])  # e
    print("6-10字符:", sample_str[6:10])  # , Wo
    
    # 子串查找
    print("\n子串查找示例:")
    target = "安hjj"
    pos = sample_str.find(target)
    if pos != -1:
        print(f"找到'{target}'于位置{pos}")
    
    # 正则匹配
    print("\n正则匹配示例:")
    import re
    chinese_pattern = re.compile(r'安[a-zA-Z0-9]{3}')
    result = chinese_pattern.search(sample_str)
    if result:
        print("匹配到中文+字母组合:", result.group())

if __name__ == "__main__":
    main()