everest% CC io0.C
everest% 

everest% a.out
0xffffffae00
0xffffffae18
Enter a filename: foo
You entered: foo
Enter another filename: bar
You entered: bar
First file name is: foo
everest% 

everest% a.out
0xffffffae00
0xffffffae18
Enter a filename: foo
You entered: foo
Enter another filename: abcdefghijklmnopqrstuvwxyz
You entered: abcdefghijklmnopqrstuvwxyz
First file name is: yz
everest% 

everest% a.out
0xffffffae00
0xffffffae18
Enter a filename: foo
You entered: foo
Enter another filename: abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz
You entered: abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuv
First file name is: yzabcdefghijklmnopqrstuv
Bus error (core dumped)
everest% 

everest% rm core