In-depth analysis of the difference between lenb function and len function

In-depth analysis of the difference between the lenb function and the len function requires specific code examples

In the Python programming language, strings are a common data type, and often Relevant operations and processing on strings are required. In the process of string processing, we often use the function of obtaining the length of a string. Python provides two built-in functions to obtain the length of a string, namely the lenb function and the len function. Although their function names are very similar, they actually have important differences in how they handle string lengths.

The len function is one of the most commonly used functions among Python's built-in functions, used to obtain the length of a string. Its use is very simple, you only need to pass the string with the length to be obtained as the parameter of the len function. The following is a simple sample code:

str1 = "Hello, World!"
length = len(str1)
print(length)  # 输出 13

In the above code, the variable str1 stores a string, the length of the string is obtained through the len function, and the result is finally printed. In this example, the output of the len function is 13, because the string "Hello, World!" has a total of 13 characters.

The lenb function is similar to the len function and is also used to obtain the length of a string, but its calculation method is different. In versions prior to Python 3, strings were stored in bytes, and different characters occupied different numbers of bytes. The lenb function is used to return the number of bytes in a string, not the number of characters. The following is a sample code using the lenb function:

str2 = "你好，世界！"
length_b = len(str2.encode('gbk'))
print(length_b)  # 输出 12

In this example, the variable str2 stores a string containing Chinese characters, and the string is converted to GBK encoding through str2.encode('gbk') The byte string, and then use the len function to get the length of the byte string. Since each Chinese character occupies 2 bytes in GBK encoding, the output result of the lenb function is 12.

It should be noted that in Python 3 and later versions, strings are stored in Unicode encoding by default, instead of being stored in bytes. Therefore, the lenb function has been deprecated in Python 3. If you want to get the number of bytes in a string, you should use the sys.getsizeof function. The following is a sample code:

import sys

str3 = "Hello, 世界！"
size = sys.getsizeof(str3)
print(size)  # 输出 62

In this example, the variable str3 stores a string containing Chinese and English characters, and the byte size of the string is obtained through the sys.getsizeof function. It should be noted that the sys.getsizeof function returns the number of bytes of memory occupied by the object, not the actual number of bytes of the string, so the result will be larger than the actual number of bytes of the string.

To sum up, the len function is used to get the number of characters in a string, and the lenb function (or sys.getsizeof function) is used to get the number of bytes in a string. Depending on the specific needs, we can choose to use different functions to obtain the length of the string.

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