Fix C File Not Opening Error

There could be various reasons why a source file cannot be opened in C language.

1. File path error: Make sure the file path is correct, including the spelling and case of the file name.
2. File not found: Please make sure the file actually exists in the specified path.
3. Issue with file permissions: unable to open file may be due to file permissions, try changing file permissions or moving the file to a different accessible path.
4. The file is in use: If the file is being used by another program or process, it may result in being unable to open the file. You can try closing other programs or processes and then attempt to open the file again.

Solution:

1. Check that the file path is correct to ensure that the file exists and the path is accurate.
2. Check the file permissions to ensure that the program has the authority to open the file.
3. Ensure that the file is not being used by any other programs.
4. You can try using other file operations functions, such as fopen(), and also check if the return value is NULL to determine if the file was successfully opened.