COP 3223H meeting -*- Outline -*-

* "Friday" problems on C loops and arrays

** string problems

*** mystrlen()
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            FOR YOU TO DO

Without using strlen() (from <string.h>),
write, in C, a function
      int mystrlen(char s[]);
that return the number of chars in s up to
the first null char ('\0').
Assume that there is a null char in s.

The following are tests using tap.h:

    ok(mystrlen("") == 0);
    ok(mystrlen("c") == 1);
    ok(mystrlen("fiddle") == 6);
    ok(mystrlen("Madam I'm Adam!") == 15);














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   Note, strlen in <string.h> is like this, 
        but returns a size_t instead of an int.


*** is_substring()
   This uses the type _Bool from <stdbool.h>
   
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           FOR YOU TO DO

Without using strstr(), write, in C,
a function
  _Bool is_substring(char sought[], char str[])
which returns true just when sought
is a substring of str. That is, when
there is some index i into str such that
sought[0] == str[i], sought[1] == str[i+1],
..., and sought[sought_len-1] == str[sought_len-1]
and all the indexes involved are legal
for both sought and str.
Assume that both sought and str
are null-terminated strings.

The following are tests using tap.h:

    ok(is_substring("abcd", "xabcd"));
    ok(is_substring("", "asdlfjlkfa"));
    ok(is_substring("fjl", "asdlfjlkfa"));
    ok(!is_substring("abba", "asdlfjlkfa"));
    ok(is_substring("Miss", "Mississippi"));
    ok(!is_substring("Fla.", "Mississippi"));
    ok(is_substring("Miss", "I love Mississippi"));
    ok(!is_substring("Miss", "I love Florida."));
    ok(!is_substring("Miss", "mississippi"));
    ok(is_substring("Miss", "Thanks, Miss"));
    ok(is_substring("dog", "x dog"));
    ok(is_substring("lazy dog",
        "The quick brown fox jumped over the lazy dog"));
    ok(is_substring("brown fox",
        "The quick brown fox jumped over the lazy dog"));
    ok(!is_substring("Drump",
        "The quick brown fox jumped over the lazy dog"));
    ok(!is_substring("Flabergasted", "Flaber"));






















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        Hint: it's helpful to write a helping function occurs_at()

        See is_substring.c in this directory.

        If there is more time, write this in Python without using in
        (or not in) or the .find() method.

** standard array problems
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           FOR YOU TO DO

In C, write a function
    int arr_min(int a[], int sz)
that takes an array of ints, a, of size sz,
and returns the minimum element in a.

The following are tests that use tap.h:

    int a3223[] = {3, 2, 2, 3};
    ok(arr_min(a3223, 4) == 2);
    int a13223[] = {1, 3, 2, 2, 3};
    ok(arr_min(a13223, 5) == 1);
    int a5041[] = {5, 0, 4, 1};
    ok(arr_min(a5041, 4) == 0);
    int a999[] = {999};
    ok(arr_min(a999, 1) == 999);

















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     Hint: it may be helpful to write a min function.

     Can write this in Python also.