Win32 API Reference: Error Handling Functions

This section provides detailed documentation for functions related to error handling within the Windows API. These functions allow you to retrieve, set, and manage error codes, providing crucial information about the success or failure of system operations.

Key Error Handling Functions

GetLastError

Retrieves the last error code set by the calling thread.

SetLastError

Sets the last error code for the calling thread.

FormatMessage

Formats a message string from a system error code.

RaiseException

Generates a specified exception.

Understanding Error Codes

System Error Codes

The Windows operating system uses a system of error codes to indicate the outcome of operations. Many Win32 API functions return a value that indicates success or failure, and if failure occurs, the specific error can be retrieved using GetLastError(). These codes are typically defined in header files like winerror.h.

Common error codes include:

  • 0 (ERROR_SUCCESS): The operation completed successfully.
  • 1 (ERROR_INVALID_FUNCTION): Incorrect function.
  • 2 (ERROR_FILE_NOT_FOUND): The system cannot find the file specified.
  • 5 (ACCESS_DENIED): Access is denied.
  • 87 (ERROR_INVALID_PARAMETER): The parameter is incorrect.

You can find a comprehensive list of system error codes in the Windows SDK documentation.

Best Practices for Error Handling

  • Always check the return value of Win32 API functions.
  • If a function indicates failure, call GetLastError() immediately to retrieve the specific error code.
  • Use FormatMessage() to convert error codes into human-readable strings for logging or user display.
  • Handle errors gracefully to prevent application crashes and provide a better user experience.
  • Consider using structured exception handling (SEH) for more complex error scenarios.