Tom Browder schrieb:
I need a map with many string pairs and I instantiate it like this:
map<const string,const string> mymap;
first const is not required, key type of a map is always const.
mymap.insert(make_pair("long_string1", "long_string_val1"));
...
mymap.insert(make_pair("long_string10000", "long_string_val10000"));
The strings generally are about 30-40 characters in length.
The source file is very long and g++ (4.0) takes a very long time (and a
large amount of memory) to compile it.
GCC does not have a very good algorithm complexity in this case it seems.
(I tried, doubling the "insert" statements quintupled compilation time).
this is compiled much faster(and will run faster):
std::pair<std::string,std::string> a[]={
std::make_pair("asdklfj","kljsfd"),
// ...
};
std::map<std::string,std::string> b(a,a + (sizeof(a) / sizeof(*a)));
I have broken the file into smaller pieces (which helps with memory usage)
but the total compile time is about the same.
Note that the map is never modified after the initial load, it is merely
used for looking up the values.
Several questions:
1. Is there a better way to initialize such a map?
2. Are there g++ options that would help?
3. Are there linker/loader tricks that would help?
Thanks.
Tom Browder
--
Stefan Strasser
