[Assorted-commits] SF.net SVN: assorted: [425] sandbox/trunk/src/cc/hash_map_strings.cc

[<yan...@us...>]

Revision: 425
          http://assorted.svn.sourceforge.net/assorted/?rev=425&view=rev
Author:   yangzhang
Date:     2008-02-14 18:28:31 -0800 (Thu, 14 Feb 2008)

Log Message:
-----------
added demo of using hash maps for strings

Added Paths:
-----------
    sandbox/trunk/src/cc/hash_map_strings.cc

Added: sandbox/trunk/src/cc/hash_map_strings.cc
===================================================================
--- sandbox/trunk/src/cc/hash_map_strings.cc	                        (rev 0)
+++ sandbox/trunk/src/cc/hash_map_strings.cc	2008-02-15 02:28:31 UTC (rev 425)
@@ -0,0 +1,52 @@
+#include <iostream>
+#include <string>
+
+// #include <ext/hash_fun.h>
+#include <ext/hash_map>
+#include <ext/hash_set>
+
+using namespace std;
+using namespace __gnu_cxx;
+
+struct eqstr
+{
+  bool operator()(const char* s1, const char* s2) const
+  {
+    return strcmp(s1, s2) == 0;
+  }
+};
+
+int
+main()
+{
+  {
+    // This doesn't compile because there is no hash function for strings.
+    // string s = "hello, world!";
+    // hash_set<string> h;
+    // h.insert(s);
+  }
+
+  {
+    // The two other arguments are required. Note that eqstr is custom-defined
+    // above.
+    hash_set< const char *, hash<const char*>, eqstr > h;
+
+    const char *s = "hello, world!";
+    h.insert(s);
+
+    const int nss = 20;
+    char *ss[nss];
+    // Duplicate s nss times into ss and h.
+    for (int i = 0; i < nss; i++) {
+      ss[i] = new char[strlen(s) + 1];
+      strcpy(ss[i], s);
+      cout << ss[i] << endl;
+      h.insert(ss[i]);
+    }
+
+    // This prints 1, which is what we want.
+    cout << h.size() << endl;
+  }
+
+  return 0;
+}


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