food chain: initial commit

cpp/food-chain/food_chain.cpp

@@ -0,0 +1,79 @@
+#include "food_chain.h"
+
+#include <string>
+
+namespace food_chain {
+
+using namespace std;
+
+
+static const char *animals[] = 
+    {"fly", "spider", "bird", "cat", "dog", "goat", "cow", "horse"};
+
+static const char *verse_phrase[] = {
+    "",
+    "It wriggled and jiggled and tickled inside her.\n",
+    "How absurd to swallow a bird!\n",
+    "Imagine that, to swallow a cat!\n",
+    "What a hog, to swallow a dog!\n",
+    "Just opened her throat and swallowed a goat!\n",
+    "I don't know how she swallowed a cow!\n",
+    "She's dead, of course!\n"
+};
+
+static const int size_of_animals = sizeof(animals) / sizeof(*animals);
+
+
+string verse(int index)
+{
+    string result;
+
+    --index;
+
+    result += string("I know an old lady who swallowed a ")
+       + animals[index]
+       + ".\n"
+       + verse_phrase[index];
+
+    if (index != size_of_animals - 1) {
+
+        for (int i = index; i > 0; --i) {
+
+            if (i == 2) {
+
+                result += "She swallowed the bird to catch the spider "
+                          "that wriggled and jiggled and tickled inside her.\n";
+            }
+            else {
+
+                result += string("She swallowed the ")
+                   + animals[i]
+                   + " to catch the "
+                   + animals[i-1]
+                   + ".\n";
+            }
+        }
+
+        result += "I don't know why she swallowed the fly. "
+                  "Perhaps she'll die.\n";
+    }
+
+    return result;
+}
+
+string verses(int from_index, int to_index)
+{
+    string result;
+
+    for (int i = from_index; i <= to_index; ++i)
+        result += verse(i) + '\n';
+
+    return result;
+}
+
+string sing()
+{
+    return verses(1, 8);
+}
+
+}