everest% cc scan3.c
everest% 

everest% a.out
Enter an alphabetic string: abcde
r = 1, str = "abcde"
everest% 

everest% a.out
Enter an alphabetic string: ab123
r = 1, str = "ab"
everest% 

everest% a.out
Enter an alphabetic string: 123ab
r = 0, str = "foo"
everest% 

everest% a.out
Enter an alphabetic string: ABCDabcd
r = 1, str = "ABCDabcd"
everest% 

everest% a.out
Enter an alphabetic string: abcdefghijklmnopqrstuvwxyz
r = 1, str = "abcdefghij"
everest%