map question

[sam]

In the following program I am getting an error when I am trying to access
i1.first. Is this valid statement?
how can I access map value through iterator? Please help me foreach
function also.


void printall(string str, int i){
cout << str<<endl;
}
int main(){

map<string,int> m;
m["One"]=1;
m["Two"]=2;
m["Three"]=3;
map<string,int> ::iterator i1;
i1= m.begin();
while(i1!=m.end ()){
cout << i1.first; // Here is the problem.
++i1;
}
//foreach(i1.begi n(),i1.end(),pr intall);
}

[Andre Kostur]

Re: map question

"sam" <sampal@nc.rr.c om> wrote in
news:gcnNa.2343 56$jp.6169814@t wister.southeas t.rr.com:
[color=blue]
> In the following program I am getting an error when I am trying to
> access i1.first. Is this valid statement?
> how can I access map value through iterator? Please help me foreach
> function also.
>
>
> void printall(string str, int i){
> cout << str<<endl;
> }
> int main(){
>
> map<string,int> m;
> m["One"]=1;
> m["Two"]=2;
> m["Three"]=3;
> map<string,int> ::iterator i1;
> i1= m.begin();
> while(i1!=m.end ()){
> cout << i1.first; // Here is the problem.
> ++i1;
> }
> //foreach(i1.begi n(),i1.end(),pr intall);
> }[/color]

i1 is an iterator into a map<string, int>, thus it "points" to a pair
<string, int>. So you'll want:

cout << i1->first;


As for your for_each, you'll want it to go from "m.begin()" to "m.end()".
And printall would need to take a (const?) reference to a pair
<string,int> in order to have a chance of working. (I unfortunately
don't use the algorithms often enough to have the details at the top of
my head....)

[sam]

Re: map question

I found the problem.
I have to access (*i1.first) instead of i1.fist.

"sam" <sampal@nc.rr.c om> wrote in message
news:gcnNa.2343 56$jp.6169814@t wister.southeas t.rr.com...[color=blue]
> In the following program I am getting an error when I am trying to access
> i1.first. Is this valid statement?
> how can I access map value through iterator? Please help me foreach
> function also.
>
>
> void printall(string str, int i){
> cout << str<<endl;
> }
> int main(){
>
> map<string,int> m;
> m["One"]=1;
> m["Two"]=2;
> m["Three"]=3;
> map<string,int> ::iterator i1;
> i1= m.begin();
> while(i1!=m.end ()){
> cout << i1.first; // Here is the problem.
> ++i1;
> }
> //foreach(i1.begi n(),i1.end(),pr intall);
> }
>
>[/color]

[sam]

Re: map question

(*i).first is correct.
"sam" <sampal@nc.rr.c om> wrote in message
news:oEnNa.2344 65$jp.6175834@t wister.southeas t.rr.com...[color=blue]
> I found the problem.
> I have to access (*i1.first) instead of i1.fist.
>
> "sam" <sampal@nc.rr.c om> wrote in message
> news:gcnNa.2343 56$jp.6169814@t wister.southeas t.rr.com...[color=green]
> > In the following program I am getting an error when I am trying to[/color][/color]
access[color=blue][color=green]
> > i1.first. Is this valid statement?
> > how can I access map value through iterator? Please help me foreach
> > function also.
> >
> >
> > void printall(string str, int i){
> > cout << str<<endl;
> > }
> > int main(){
> >
> > map<string,int> m;
> > m["One"]=1;
> > m["Two"]=2;
> > m["Three"]=3;
> > map<string,int> ::iterator i1;
> > i1= m.begin();
> > while(i1!=m.end ()){
> > cout << i1.first; // Here is the problem.
> > ++i1;
> > }
> > //foreach(i1.begi n(),i1.end(),pr intall);
> > }
> >
> >[/color]
>
>[/color]

[Chris \( Val \)]

Re: map question


"sam" <sampal@nc.rr.c om> wrote in message
news:gcnNa.2343 56$jp.6169814@t wister.southeas t.rr.com...
| In the following program I am getting an error when I am trying to access
| i1.first. Is this valid statement?
| how can I access map value through iterator? Please help me foreach
| function also.
|
|
| void printall(string str, int i){
| cout << str<<endl;
| }

void printall( std::pair<std:: string, int> P ) {
std::cout << P.first << ", " << P.second << endl;
}

| int main(){
|
| map<string,int> m;
| m["One"]=1;
| m["Two"]=2;
| m["Three"]=3;
| map<string,int> ::iterator i1;
| i1= m.begin();
| while(i1!=m.end ()){
| cout << i1.first; // Here is the problem.

std::cout << i1 -> first;

| ++i1;
| }
| //foreach(i1.begi n(),i1.end(),pr intall);
| }

std::for_each( m.begin(), m.end(), printall );

Cheers.
Chris Val

[Artie Gold]

Re: map question

sam wrote:[color=blue]
> (*i).first is correct.[/color]

Which is typically expressed as `i->first' (as per Andre's reply).
[color=blue]
> "sam" <sampal@nc.rr.c om> wrote in message
> news:oEnNa.2344 65$jp.6175834@t wister.southeas t.rr.com...
>[color=green]
>>I found the problem.
>>I have to access (*i1.first) instead of i1.fist.
>>
>>"sam" <sampal@nc.rr.c om> wrote in message
>>news:gcnNa.23 4356$jp.6169814 @twister.southe ast.rr.com...
>>[color=darkred]
>>>In the following program I am getting an error when I am trying to[/color]
>>[/color]
> access
>[color=green][color=darkred]
>>>i1.first. Is this valid statement?
>>> how can I access map value through iterator? Please help me foreach
>>>function also.
>>>
>>>
>>>void printall(string str, int i){
>>> cout << str<<endl;
>>>}
>>>int main(){
>>>
>>> map<string,int> m;
>>> m["One"]=1;
>>> m["Two"]=2;
>>> m["Three"]=3;
>>> map<string,int> ::iterator i1;
>>> i1= m.begin();
>>> while(i1!=m.end ()){
>>> cout << i1.first; // Here is the problem.
>>> ++i1;
>>> }
>>> //foreach(i1.begi n(),i1.end(),pr intall);
>>>}
>>>
>>>[/color]
>>
>>[/color]
>
>[/color]

HTH,
--ag

--
Artie Gold -- Austin, Texas



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