Hi Ed --
As for docs, did you check the net? It's amazing what can be found with
google -- and also, don't forget your IDE and the docs distributed with
that.
Sorry I'm not much help -- I just have my head scattered among a million
activities and have C++ on the back burner of late.
But back to your other question, you ask:
can you check to see if a map element has been subscripted with the same
string?
The answer to this is "huh?" -- I mean, what are you asking? A map is an
associative array -- that is you map an arbitrary type to another arbitrary
type. Now you can do something like the following:
map<string,int> countermap;
countermap["Edward"]++;
and so forth -- and you can't have more than one "Edward" entry in your map.
Perhaps that is where the confusion lies.
However, you can have multiple instances of an object on the right hand
side -- but if you want to find all the lefthand strings that map to 3, for
example, you will have to loop through the map elements and simply collect
them -- or better yet, create a map that maps the other direction -- i.e.,
map<int,string>, or else just an array of strings. That is expensive and a
resource hog, but something to consider.
Now to loop through a map you need to use a map::iterator -- I can go dig up
a quick example of that if you like, or you can go and look at the docs.
An iterator is a special type that is a member of class map that supports
looping through all the elements of the map in the order they were entered..
It is really quite nice.
HTH
--le
----- Original Message -----
From: "Edward Przybylek" <przy5100@xxxxxxxxxxxxxxxx>
To: <program-l@xxxxxxxxxxxxx>
Sent: Thursday, September 29, 2005 10:27 PM
Subject: [program-l] Re: C++ Template Question
Hi Laura,
Thanks for the explanation. It's actually beginning to make
sense. I think the thing that was throwing me is the subscripting of
a map element with a string. Do you know if there's any runtime
checking to see if a map element has been subscripted with the same string?
Do you know where I might get some accessible documentation on the
map and vector libraries? I'm sure I can obtain some documentation
in a few days but I have a deadline that doesn't allow for a few
days. Possibly something on the MicroSoft site? Thanks an awful lot
for all your help.
Take care,
Ed Przybylek <a slightly more educated C++ programmer>
At 04:19 PM 9/29/2005, you wrote:
>Hi there -- I can answer this simply (hopefully...).
>
>First of all, C++ declarations of all kinds have declaration syntax that
>hints at the syntax required to use the object being declared.
>For example, the old C syntax
>int* p[10];
>
>indicates that to get down to the int you have to type *p[i], where i is an
>int.
>
>Ok, it gets a little nebulous when you get into templates, and the
>declaration does not match usage quite the same way.
>Now look carefully at what you want to do. Vector[string> is overloades
>operator[] to take an integer subscript and return a string. So to get the
>third element there you need to provide a vector and subascript it with 3.
>But how do you get at the vector? The answer is that
>Map<string,Vector<string> > mymap; declares a map that overloads operator[]
>to take a string subscript and return a vector -- mapping a string to a
>vector in other words.
>So type
>
>string j3 = mymap["Joe"][3];
>
>to get at the final string.
>
>I know this requires some study of the Vector and Map libraries. It is not
>really a C++ question, but rather a library definition question.
>
>So if you are not sure of a library, go to whatever library documentation
>you have.
>
>HTH
>--le
>
>
>----- Original Message -----
>From: "Edward Przybylek" <przy5100@xxxxxxxxxxxxxxxx>
>To: "Program-L" <program-l@xxxxxxxxxxxxx>
>Sent: Wednesday, September 28, 2005 8:18 PM
>Subject: [program-l] C++ Template Question
>
>
>Hi all,
>
>I encountered the following declaration in one of the programs I'm
>modifying/enhancing at work:
>
>map<string, vector<string>> mymap;
>
>How does one reference the various elements of this structure. In
>other words, How do I access the fifth or sixth element in the
>vector? I'm sure that to you C++ experts this is obvious but to us
>novices (folks like me), it doesn't appear to be that straight
>forward. If you're willing to explain the above, maybe you could
>take a crack at the following:
>
>map<string, vector<string, string>> mymap;
>
>The question is the same. How do I get at the various elements of
>the vector in this structure?
>
>What ever happened to the days of assembler, Fortran, Cobol etc. ...
>in otherwords, the "good old days"? As always, any help greatly
>appreciated.
>
>Take care,
>Ed Przybylek
>
>
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