How to use the repr() function in Python to obtain the string representation of an object

How to use the repr() function in Python to obtain the string representation of an object

Introduction:
In Python, we often need to convert objects into characters It can be output, stored or passed to other functions in the form of a string. The repr() function is one of the commonly used functions in Python, used to obtain the string representation of an object. This article will introduce how to use the repr() function and attach code examples.

1. The role of the repr() function:
In Python, each object has a default string representation, which is used to display the basic information of the object. But in some cases, we may need to obtain more object information, including detailed attributes, status, etc. of the object. At this time, you can use the repr() function to obtain the string representation of the object. The string returned by the
repr() function has the following characteristics:

1. The string is enclosed in single quotes or double quotes.
2. Strings can be re-converted into original objects using the eval() function.
3. The string form contains detailed information of the object, such as class name, attributes, status, etc.

2. How to use the repr() function:
The use of the repr() function is very simple. Just add a period "." after the object, followed by repr. (), that is:
repr(object)

Code example:
The following is a simple code example that demonstrates how to use the repr() function to obtain the string representation of an object:

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
    
    def __repr__(self):
        return f"Person('{self.name}', {self.age})"
        
    def __str__(self):
        return f"Person: {self.name}, {self.age}"

person = Person("Tom", 25)

# 使用repr()函数输出对象的字符串表示形式
print(repr(person))  # 输出：Person('Tom', 25)

In the above code, we define a Person class, which contains two attributes name and age. In the class, we override the __repr__() method, which will be called by the repr() function and return a string in the form of Person('Tom', 25). We also overridden the __str__() method, which will be called by the print() function and return a string in the form of Person: Tom, 25. When printing the person object, use the repr() function to obtain the string representation of the object.

3. The difference between the repr() function and the str() function:
In the above code example, we have rewritten the __repr__() method and the __str__() method at the same time. This is because in Python, there is a difference between the repr() function and the str() function. The string returned by the repr() function is used for development and debugging, while the string returned by the str() function is used for user display. Normally, we should override both methods to use different string representations in different scenarios.

For example, when we print the person object directly, the __str__() method will be called, and the output is: Person: Tom, 25. When we use the repr() function to obtain the string representation of the person object, the __repr__() method is called, and the output is: Person('Tom', 25). The difference between the two is that the string returned by the repr() function contains more detailed information, which is convenient for development and debugging.

Conclusion:
This article introduces how to use the repr() function to obtain the string representation of an object. By overriding the __repr__() method, we can customize the string representation of the object and return it using the repr() function. The repr() function is often used for development and debugging, and can easily view the properties and status of objects. In actual programming, we should rewrite both the __repr__() method and the __str__() method according to the actual situation to use different string representations in different scenarios.

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