Compare the usage scenarios and functions of lenb function and len function

Usage scenarios and functional comparison of lenb function and len function

In Python development, two functions are often used: lenb function and len function, which are respectively Used to count the number of bytes and characters in a string. Although their names are similar, their usage scenarios and functions are different.

First, let’s take a look at the usage scenarios and functions of the len function.

The len function is one of Python's built-in functions. Its function is to return the length or number of elements of an object. In strings, the len function is often used to count the number of characters in a string. Here is a simple example:

str1 = "Hello World"
print(len(str1))  # 输出：11

In the above example, we defined a string str1 and used the len function to calculate the number of characters in the string. As you can see, the len function returns the number of characters in the string, not the number of bytes.

Next, let’s take a look at the usage scenarios and functions of the lenb function.

The lenb function is a custom function whose function is to return the number of bytes in a string. By using the lenb function, we can accurately calculate the storage space occupied by a string. The following is an example:

def lenb(s):
    return len(s.encode("utf-8"))

str2 = "你好，世界"
print(lenb(str2))  # 输出：12

In the above example, we define a function named lenb, which converts the string to UTF-8 encoding and then counts the number of bytes. By using the lenb function, we get the number of bytes occupied by the string "Hello, world", and the result is 12.

It should be noted that in most cases, the results of the len function and the lenb function are the same. But in some special cases, their results will be different. For example, when the string contains non-ASCII characters, the len function returns the number of characters, and the lenb function returns the number of bytes.

The following is a more specific example to better understand the difference between the len function and the lenb function:

str3 = "中文字符"
print(len(str3))   # 输出：4
print(lenb(str3))  # 输出：9

In the above example, the string str3 contains two Chinese characters, Since the encoding of Chinese characters usually takes 3 bytes, the value returned by the lenb function is 9, and the value returned by the len function is 4.

To sum up, the len function and the lenb function use different calculation methods when calculating the length of a string. The len function returns the number of characters in the string, and the lenb function returns the number of bytes occupied by the string. When using it, we should choose the appropriate function to calculate the length of the string based on actual needs.

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