In reply to Gayathrishetty:
I do not understand what file name you are trying to create. There are many ways to do this of which $sformatf would be one of them. All of these are equivalent:
file = $fopen("my_file_name");
file = $fopen({"my_","file_", name"});
file = $fopen($sformatf("my_%s_name","file");
