How does the try/catch block in C++ function exception handling work?

In C, try blocks contain code that may throw exceptions, and catch blocks are used to handle specific types of exceptions. A try/catch block allows a program to resume or continue execution gracefully, preventing unexpected termination. When an exception occurs, control is passed to a catch block with a matching type qualifier, such as try { ... } catch (const std::exception& e) { ... }.

How to handle function exceptions in the try/catch block in C

Exception handling is a crucial mechanism in software development. Allows programs to gracefully resume or continue execution when abnormal conditions occur. In C, you can use try and catch blocks to handle exceptions thrown within a function.

How try/catch blocks work

try Blocks are used to contain code that may throw exceptions. If the code in the try block executes successfully, jump directly to the line of code that immediately follows. If code in a try block throws an exception, control is passed to the corresponding catch block.

catch block is used to handle exceptions of a specific type, and it is always followed by a type qualifier. For example, the following code snippet will handle all exceptions of type std::exception:

try {
  // 可能引发异常的代码
} catch (const std::exception& e) {
  // 处理异常
}

Practical case

Suppose we have a functionread_file(), which reads data from a file. This function may raise a std::ifstream::failure exception if the file does not exist or cannot be read. The following code snippet demonstrates how to use try and catch blocks to handle this exception:

void read_file(const std::string& filename) {
  std::ifstream file(filename);

  // 文件读取操作可能会引发 std::ifstream::failure 异常
  try {
    // 读文件操作
  } catch (const std::ifstream::failure& e) {
    std::cerr << "读取文件失败: " << e.what() << std::endl;
  }
}

In this case, if read_file() The function cannot successfully read the file, the program will print an error message and continue execution.

Note:

• Each try block can have multiple catch blocks, each catch blocks are used to handle different exception types.
• If the code in the try block does not throw an exception, no catch blocks will be executed.
• If an unhandled exception escapes a function, the program terminates unless there is an unspecified operator.

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