How Can I Get the Specific Error Message When an `ifstream` Fails to Open a File?

Obtaining Error Message for ifstream Open Failures

When attempting to open a file using ifstream, the open method may fail due to various reasons. To obtain the specific error message associated with the failure:

Understanding Error Codes

Every system call that fails updates the errno value. This value provides information about the cause of the failure.

Retrieving Error Message

To obtain the error message as a string, utilize the following code snippet:

Important Note for Multithreaded Applications

In multithreaded applications, errno is a global value. Thus, if another system call triggers an error between f.open and accessing errno, you may encounter issues.

POSIX Systems

On POSIX-compliant systems, errno is thread-local, eliminating this concern.

e.what() Method

Initially, e.what() was considered a more C -style approach for obtaining the error message. However, the string returned by this function is implementation-dependent and often lacks meaningful information in G 's libstdc .

The above is the detailed content of How Can I Get the Specific Error Message When an `ifstream` Fails to Open a File?. For more information, please follow other related articles on the PHP Chinese website!