biometric fingerprint attendance systems

I tried to in this code but i got error… anyone know how to fix this

There is no error. There are two warnings.

You need to understand the difference between warnings and errors. A warning is the compiler telling you there is something in the code that could possibly cause a problem but doesn’t cause the compilation to fail. An error is a problem with the code that causes compilation to fail. In this case you have posted warnings not errors.

The first warning is fairly self explanatory. You declared a function as returning uint8_t, but then you are not returning anything from the function. Maybe you need to spend some time studying the reference page for return:
and perhaps for void as well:

The second warning is because your dynamic memory use from global variables is above the warning threshold of 75% of available memory. The problem is that local variables also use memory. If the global + local dynamic memory use ever exceed 100% of what’s available, your program will crash. If you want help with reducing the dynamic memory usage, you would need to post your code:

If possible, you should always post code directly in the forum thread as text using code tags:

  • Do an Auto Format (Tools > Auto Format in the Arduino IDE or Ctrl + B in the Arduino Web Editor) on your code. This will make it easier for you to spot bugs and make it easier for us to read.
  • In the Arduino IDE or Arduino Web Editor, click on the window that contains your sketch code.
  • Press “Ctrl + A”. This will select all the text.
  • Press “Ctrl + C”. This will copy the selected text to the clipboard.
  • In a forum reply here, click on the reply field.
  • Click the </> button on the forum toolbar. This will add the forum’s code tags markup to your reply.
  • Press “Ctrl + V”. This will paste the sketch between the code tags.
  • Move the cursor outside of the code tags before you add any additional text to your reply.
  • Repeat the above process if your sketch has multiple tabs.

This will make it easy for anyone to look at it, which will increase the likelihood of you getting help.

If the sketch is longer than the 9000 characters maximum allowed by the forum, then it’s OK to add it as an attachment. After clicking the “Reply” button, you will see an “Attachments and other settings” link.

When your code requires a library that’s not included with the Arduino IDE please post a link (using the chain links icon on the forum toolbar to make it clickable) to where you downloaded that library from or if you installed it using Library Manger (Sketch > Include Library > Manage Libraries in the Arduino IDE or Libraries > Library Manager in the Arduino Web Editor) then say so and state the full name of the library.