On code copy pasted from Notepad into a Code Block macro, Confluence removes all the newlines from the block.

Steps:

Enter this in Notepad:

printf("Hello world");

printf("Testing testing");

printf("Where are my newlines?");

return 0;

Make a new Confluence page. Insert a Code Block, language C#.

Copy block from Notepad.

Paste into Code Block.

Notice that all the newlines are gone.