Casting vs. `as` in C#: When Should I Use Which?

Type conversion in c#:

Comprehensive guidelines for keywords and forced conversion as During the development of the interface, type conversion and object conversion are common tasks. In C#, we mainly have two methods to achieve this conversion: forced conversion and

keywords. Although the goals of these two technologies are to change the data type, there are subtle differences between them, which will affect the operation of the program.

as Forced conversion

Mandatory conversion refers to transforming one object from one type to another. This can be achieved through grammar , where indicates the required data type,

is a variable we want to convert. For example:

(目标类型)对象 目标类型 This code is forced to convert the objects stored in 对象 to

and assign it to the variable

_myCls1 = (MyClass)_MyObj;

. If the conversion is successful, <包> now contains reference to the underlying

object. However, if the conversion fails, _MyObj abnormalities will be thrown. MyClass _myCls1 _myCls1 <<> Keywords MyClass InvalidCastException

Unlike the mandatory conversion,

The keyword executes a security conversion, and if the conversion fails, it returns . This avoids abnormal risks and allows writing air security code. as

In this code, if the conversion from

to as is successful, the variable null will reference the conversion object. If the conversion fails, <被> will be assigned to

. When we expect the conversion to fail and want to handle the

_myCls2 = (_MyObj as MyClass);

value elegantly, this method is recommended.

_MyObj Performance impact MyClass _myCls2 _myCls2 In terms of performance, the modern instant (JIT) compiler will optimize the compulsory conversion and null keywords to make its performance similar. Although the mandatory conversion may be slightly faster in some cases, the difference is slightly insignificant and will not significantly affect program performance. null

Recommended method

Which type of conversion method is better depends on specific use cases. If we are convinced that the conversion will be successful, the mandatory conversion provides a more efficient choice. However, if the conversion may fail or we want to handle the

value safely, the

keyword is a safer choice. as

Generally speaking, the following standards may help:

Confristic that the conversion will be successful and requires the maximum performance, use forced conversion.

When the conversion may fail or wants to handle null values ​​safely, use as keywords.

Avoid using and then forced conversion or

keywords, because it may introduce unnecessary types of examination and reduce performance.

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