everest% CC io1.C
everest% 

everest% a.out
Enter a filename: foo
You entered: foo
Enter another filename: abcdefghijklmnopqrstuvwxyz
You entered: abcdefg
First file name is: foo
everest% 

everest% a.out
Enter a filename: abcdefghijklmnopqrstuvwxyz
You entered: abcdefg
Enter another filename: You entered: hijklmn
First file name is: abcdefg
everest%