Exception handling in C++ frequently asked interview questions

In C programming, exception handling is a very important concept. Exceptions refer to unpredictable errors that occur when a program is running. These errors may cause the program to crash, seriously affecting the stability and reliability of the program. To deal with these unpredictable errors, C provides an exception handling mechanism. In C programming, exception handling is a very important concept and one of the common interview questions. Next, let's take a look at common interview questions about exception handling in C.

1. What is exception handling?

Exception handling refers to using certain processing methods to restore the normal execution of the program when an unpredictable error occurs while the program is running. In C, exception handling can be implemented through try-catch statements. When an exception occurs in the try code block, the program will jump to the catch code block to execute the corresponding exception handling logic.

2. What is the syntax of try-catch statement?

The syntax of the try-catch statement is as follows:

try {
    // 可能会发生异常的代码块
}
catch (exception_type& e) {
    // 异常处理逻辑
}

Among them, the try code block contains code that may cause exceptions, and the catch code block contains exception handling logic. exception_type is the exception type, indicating the type of exception that needs to be caught. e is an exception object, representing the captured exception object.

3. What are the exception types in C?

Exception types in C include system-defined exception types and user-defined exception types. These exception types usually inherit from the std::exception class. Common exception types are:

• std::runtime_error: Indicates that a runtime error has occurred.
• std::logic_error: Indicates that a logic error has occurred.
• std::bad_alloc: Indicates memory allocation failure.
• std::range_error: Indicates that an index outside the valid range was accessed.

In addition, users can customize exception types according to their own needs.

4. Under what circumstances should exception handling be used?

Exception handling should be used when an uncontrollable error is encountered during program running. For example, if the program encounters illegal parameters, file read and write errors, memory allocation failure, etc., these are all situations that require the use of exception handling.

5. What is exception security?

Exception safety means that when a program throws an exception, it can ensure that the program can recover normally. The STL in the C standard library is a typical example of exception safety. When adding elements to an STL container, if an exception occurs while adding the element, STL will automatically restore the container to the state before adding the element, thereby ensuring program security.

6. How to throw exception in C?

In C, you can use the throw statement to throw an exception. The throw statement accepts one parameter, which is usually an exception object. When the program encounters a throw statement, it will throw the exception object and then jump to the try-catch statement to execute the corresponding exception handling logic.

7. What is an exception chain?

When an exception occurs in the program, the exception will be captured in the try code block and the corresponding exception handling logic will be executed. During this process, the exception may be thrown again and then caught by another catch block. Such an exception handling method is an exception chain. Exception chains can help us better track exceptions and find the specific location where the exception occurs.

Summary:

Exception handling is a very important concept in C programming and one of the common questions in interviews. When an uncontrollable error is encountered in a program, exception handling can be used to restore normal execution of the program. When using exception handling, you need to pay attention to concepts such as exception types, exception safety, and exception chains in order to better handle exceptions.

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