static void AddTally(Hashtable<String, double> & tallies, const char * verb, uint64 startTime, uint32 numItems)
{
uint64 elapsed = (GetRunTime64()-startTime);
double itemsPerSecond = ((double)numItems*((double)MICROS_PER_SECOND))/elapsed;
printf(" It took " UINT64_FORMAT_SPEC" microseconds to %s " UINT32_FORMAT_SPEC" items, so we %s %.0f items per second\n", elapsed, verb, numItems, verb, itemsPerSecond);
*(tallies.GetOrPut(verb)) += itemsPerSecond;
}
int main(int argc, char ** argv)
{
CompleteSetupSystem css;
PrintExampleDescription();
Hashtable<String, int> table;
// If we know up-front a limit on the number of items we are likely to place
// into the table, we can reserve that many slots in advance, and thereby
// avoid any chance of the Hashtable having to reallocate its internal array
// while we are adding items to it.
//
// That avoids some inefficiency, and it also means we don't have
// to worry about out-of-memory errors, or the memory-locations of key or
// value-items changing, while populating the table.
if (table.EnsureSize(20) != B_NO_ERROR) WARN_OUT_OF_MEMORY;
// Put some initial data into the table
table.Put("One", 1);
table.Put("Two", 2);
// table.GetWithDefault() returns a reference to the value of the specified
// key, or a reference to a default-constructed value otherwise.
const int & oneRef = table.GetWithDefault("One");
const int & twoRef = table.GetWithDefault("Two");
const int & threeRef = table.GetWithDefault("Three");
printf("A: OneRef=%i twoRef=%i threeRef=%i\n", oneRef, twoRef, threeRef);
printf("\n");
// The [] operator is a synonym for GetWithDefault()
printf("B: table[\"One\"]=%i table[\"Two\"]=%i table[\"Three\"]=%i\n", table["One"], table["Two"], table["Three"]);
printf("\n");
// GetOrPut() returns a pointer to the value of the given key, if the key is present
// If the key isn't present, it places a key/value pair into the Hashtable and returns
// a pointer to the (default-constructed) placed value. This is very useful when
// demand-allocating records.
int * pEight = table.GetOrPut("Eight");
printf("C: table.GetOrPut(\"Eight\") returned %p\n", pEight);
if (pEight) *pEight = 8;
else WARN_OUT_OF_MEMORY; // GetOrPut() returns NULL only on memory-exhaustion
printf("\n");
// The next time we call GetOrPut() we'll get a pointer to the existing value
pEight = table.GetOrPut("Eight");
printf("C: Second call to table.GetOrPut(\"Eight\") returned %p (aka %i)\n", pEight, pEight?*pEight:666);
printf("\n");
// We can also call GetOrPut() with a suggested default-value which will be
// placed into the key/value pair if the supplied key isn't already present.
int * pNine = table.GetOrPut("Nine", 9);
printf("C: table.GetOrPut(\"Nine\", 9) returned %p (aka %i)\n", pNine, pNine?*pNine:666);
printf("\n");
// PutAndGet() is similar to GetOrPut() except it *always* places a value.
// (if the key already existed in the table, its value will be overwritten)
int * pTen = table.PutAndGet("Ten", 10);
printf("D: table.PutAndGet(\"Ten\", 10) returned %p (aka %i)\n", pTen, pTen?*pTen:666);
// Demonstrate PutAndGet()'s overwrite of the previous value
pTen = table.PutAndGet("Ten", 11);
printf("E: table.PutAndGet(\"Ten\", 11) returned %p (aka %i)\n", pTen, pTen?*pTen:666);
// If you want a Hashtable with keys only and don't need values at all
// (similar to e.g. a std::unordered_set<>), a good way to get that is
// to use the Void class as your value-type. A Void object is just a
// placeholder that contains no data.
Hashtable<String, Void> keysOnlyTable;
(void) keysOnlyTable.PutWithDefault("Blue");
(void) keysOnlyTable.PutWithDefault("Red");
(void) keysOnlyTable.PutWithDefault("Green");
printf("\n");
return 0;
}