Re: assignment/initialization of container - map

From:
"xuatla" <xuatla@gmail.com>
Newsgroups:
comp.lang.c++
Date:
18 Jul 2006 15:55:25 -0700
Message-ID:
<1153263325.786941.136450@p79g2000cwp.googlegroups.com>
Thomas Tutone wrote:

xuatla wrote:

I want to define a map:

std::map<string, int> myMap;

e.g., the score of students. Then I can assign the value as follows:
myMap["stud1"] = 90;
myMap["stud2"] = 60;
...

My question now is: can I assign the name of many students in one line?
e.g., for array we have the following way:
     int myArray[] = { 1, 3, 4, 5 };

Do we have similar way for map?


No.

std::map<string, int> myMap = { ("stud1", 90), ("stud2", 60) };
                   // wrong code

Another question: how can I print the score of a given student's name?

void getScore(std::map<string, int> myMap, const std::string& stuName)
{
     return myMap.find(stuName)->second();
}

Is this correct? Any better solution?


First, unless you want to DRASTICALLY inefficient, better to pass the
map by reference instead of by value. Second, you can't return a value
if you declare the function void. Finally, although theoretically
slightly less efficient, more clear in my view is to use operator[] and
dump the separate function altogether:

    myMap[stuName]

or if you insist on the separate function, make it:

int getScore(std::map<string, int>& myMap, const std::string& stuName)
{
    return myMap[stuName];
}


Thanks for your reply. "void" is my typo. I think I was dumb when I
stated my question in above way. I got the answers from the replies
here now. Thanks to all.

- X

btw : an off-topic question: I use thunderbird to read newsgroups.
Today I found that I couldn't read the latest threads in it (the most
recent ones shown was posted at yesterday). Is there anyone else
encountered same questions? Which software do you think is best for
newsgroups reading/posting? Now I am using Google groups to read the
threads here. (I just came back from Mars and this is my first time
using Google groups for newsgroups...)

Best regards,

Tom

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