defget_first_number(string):numbers=[charforcharinstringifchar.isdigit()]ifnumbers:returnnumbers[0]else:returnNone# 测试代码string1="abc123def456"number1=get_first_number(string1)print(number1)# 输出:1string2="abcxyz"number2=get_first_number(string2)print(number2)# 输出:None 1. 2. 3. 4...
charlie_grade = student_grades.get("Charlie") # .jpg 或 None(如果不存在) # 使用get()避免KeyError default_grade = student_grades.get("David", 75) # 当键不存在时返回默认值2.1.2.2 字典的增删改操作 字典提供了相应的方法来操作键值对: •增:直接赋值或使用update() •删:pop()、popitem()...
tostr): 62 """maketrans(frm, to) -> string 63 64 Return a translation table (a string of 256 bytes long) 65 suitable for use in string.translate. The
4 Beginning with Python 1.6, many of these functions are implemented as 5 methods on the standard string object. They used to be implemented by 6 a built-in module called strop, but strop is now obsolete itself. 7 8 Public module variables: 9 10 whitespace -- a string containing all ...
a nice string representation of the object. | If the argument is a string, the return value is the same object. | | Method resolution order: | str | basestring | object | | Methods defined here: | | __add__(...) | x.__add__(y) <==> x+y | | __contains__(...) | x...
char in key_string: # 计算key所有字符的ASCII值的和 count_char += ord(key_char) # ord()函数用于求ASCII值 length = len(str(count_char))if length > 3 : # 当和的位数大于3时，使用平方取中法，保留中间3位 mid_int = 100*int((str(count_char)[length//2-1])) \ + 10*...
3.1.1 字符串(String) 3.1.1.1 字符串的创建与访问 字符串是Python中最常见的不可变类型之一。创建字符串时,可以使用单引号'或双引号"包裹字符序列。 text="Hello, World!"# 创建字符串first_char=text[0]# 访问第一个字符 请注意,尽管字符串提供了诸如replace()、upper()等看似“修改”字符串的方法,实际上...
使用in关键字可以检查一个字符串是否包含另一个子字符串。 substring = 'Python' substring in string2 (4)索引(Indexing) 使用方括号和索引可以获取字符串中特定位置的字符。索引从 0 开始。 char_at_index_2 = string1[2] # 结果为 'l' (5)切片(Slicing) ...
On execution of the program, we will get the following output. OUTPUT 1 2 3 'a' in 'character' exists at index 2 The find() is a built-in method in Python that searches for a substring in a string. It returns the index of the first occurrence of the substring or -1 if not ...
12 document.title = sub + firstChar; //对字符串进行新的拼接 13 } 14 15 setInterval('run()', 1000); //使用interval每秒执行然后达到跑马灯的目的 16 17 18 19 20 21 22 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12....