String str1 = "Hello"; String str2 = new String(str1);和这个String(String original)有关系吗
时间: 2023-11-12 13:24:06 浏览: 55
是的,这两段代码有关系。
第二行代码 `String str2 = new String(str1);` 使用了 `String` 类的构造函数 `String(String original)`,该构造函数会创建一个新的字符串对象,其值是传递给它的字符串参数 `str1` 的副本。因此,`str2` 的值与 `str1` 的值相同,但它们是两个不同的字符串对象。
需要注意的是,`String` 类是不可变的,因此在创建了一个 `String` 对象之后,它的值不能被修改。如果需要修改字符串,可以使用 `StringBuilder` 或 `StringBuffer` 类。
相关问题
table = str.maketrans('', '', string.punctuation)
This line of code creates a translation table that can be used to remove all punctuation marks from a string. Specifically, it uses the string method `maketrans()` to create a translation table that maps each punctuation mark to None (i.e. it removes them from the string). The first two arguments of `maketrans()` are empty strings, which means that no characters will be replaced by other characters. The third argument, `string.punctuation`, is a predefined string in the `string` module that contains all punctuation marks.
This translation table can be passed to the `translate()` method of a string to remove all punctuation marks. For example:
```
text = "Hello, world!"
clean_text = text.translate(table)
print(clean_text) # Output: "Hello world"
```
Here, `table` is the translation table created by `maketrans()`, and `clean_text` is the original text with all punctuation marks removed.
str = "Hello World" x = len(str) def reversed_str(): reversed_str = "" for i in range(x-1, -1, -1): #从第10个到第0个数 reversed_str = str[i] +reversed_str return reversed_str str = "Hello World" print("The original str is: ") print(str) str2 = reversed_str() print = ("The reversed string is: ") print(str2)哪里有问题
这段代码定义了一个字符串变量 str,其值为 "Hello World",并且通过 len() 函数获取了该字符串的长度,将其赋值给变量 x。接着定义了一个名为 reversed_str() 的函数,该函数用于将字符串 str 反转。在函数中,定义了一个空字符串 reversed_str,然后通过 for 循环倒序遍历字符串 str 中的每个字符,并将其依次添加到 reversed_str 中。最后,函数返回反转后的字符串 reversed_str。