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.begin(),i1.end(),printall);
}

 

[Andre Kostur]

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.begin(),i1.end(),printall);
}

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]

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

 

[sam]

(*i).first is correct.

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

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.begin(),i1.end(),printall);
}

 

[Chris \( Val \)]

| 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:air<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.begin(),i1.end(),printall);
| }

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

Cheers.
Chris Val

 

[Artie Gold]

(*i).first is correct.

Which is typically expressed as `i->first' (as per Andre's reply).

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

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.begin(),i1.end(),printall);
}

HTH,
--ag