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Annotation of 42BSD/usr.lib/learn/C/L30.1a, revision 1.1.1.1

1.1       root        1: #print
                      2: Write a subroutine named "locn(s,c)" which expects two
                      3: arguments: the first is a pointer to characters 's' which
                      4: points to a null-terminated string, and the second
                      5: is a character 'c' which is to be searched for in the
                      6: string 's'.  If the character 'c' does not
                      7: appear in the string return 0; otherwise return a pointer
                      8: to the position of 'c' in the string. Name the program "locn.c";
                      9: as usual, compile and test it and then type "ready".
                     10: #once #create Ref
                     11: 0
                     12: 19
                     13: 0
                     14: 25
                     15: 0
                     16: #once #create tzaqc.c
                     17: char *alpha "abcdefghijklmnopqrstuvwxyz";
                     18: main()
                     19: {
                     20:        extern char *locn();
                     21:        printf("%d\n", locn(alpha, '+'));
                     22:        printf("%d\n",locn(alpha, 't')-alpha);
                     23:        printf("%d\n",locn(alpha, 'a')-alpha);
                     24:        printf("%d\n",locn(alpha, 'z')-alpha);
                     25:        printf("%d\n",locn("", 'z'));
                     26: }
                     27: #user
                     28: cc tzaqc.c locn.o
                     29: a.out  >value
                     30: #cmp value Ref
                     31: #succeed
                     32: /* Try this: */
                     33: 
                     34: char *
                     35: locn (s, c)
                     36: char *s;
                     37: {
                     38:        for( ; *s; s++)
                     39:                if (*s == c)
                     40:                        return(s);
                     41:        return(0);
                     42: }
                     43: #log
                     44: #next
                     45: 31.1a 10

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