How to pass map as default parameter to a function

[Abhinay]

hi,
Can any buddy help me to pass map as default orgunment to a function.
I have a map as below,

std::map<std::string,std::string> myStringMap
and i want to pass this map to a function as default orgunment.

(
as we allways pass an int or long as default orgunment to function like this
void fun( int iRollNumber=10 );
//here default value of iRollNumber is 10
)

So can we do the same in case of map . If yes then how ???

plz help me ,

thank's in advance.

Regards,
Abhinay

[Motoma]

hi,
Can any buddy help me to pass map as default orgunment to a function.
I have a map as below,

std::map<std::string,std::string> myStringMap
and i want to pass this map to a function as default orgunment.

(
as we allways pass an int or long as default orgunment to function like this
void fun( int iRollNumber=10 );
//here default value of iRollNumber is 10
)

So can we do the same in case of map . If yes then how ???

plz help me ,

thank's in advance.

Regards,
Abhinay

I don't think you can use a variable as a default value. What you may be able to do instead is overload the function, where a call without arguments performs a call to the original function specifying the default value.

[horace1]

no problem so long as you have a map to use as a default, e.g.

#include <iostream>
#include <map>
using namespace std;
 
map<const char*, int> defaultClass;    // default map
 
// print contents of map (or the default)
void printMap(map<const char*, int>  s = defaultClass)
{ 
 cout << "george is " << s["george"] << " years old" << endl;
 map<const char*, int>::iterator it;
  for( map<const char*, int>::iterator iter = s.begin(); iter != s.end(); iter++ ) {
    cout << (*iter).first << " is " << (*iter).second << " years old" << endl;
}
}
 
int main()
{
  // setup default class names and ages  and print it
  defaultClass["henry"] = 5;
  defaultClass["george"] = 6;
  defaultClass["susan"] = 8;
  defaultClass["jenny"] = 12;
  cout << "default class " << endl;
  printMap();
  // setup class names and ages and print it
  map<const char*, int> class1;
  class1["sam"] = 3;
  class1["george"] = 4;
  class1["mary"] = 89;
  class1["sally"] = 11;
  cout << "\nclass " << endl;
  printMap(class1);
  cin.get();
}
 

this will display
default class
george is 6 years old
george is 6 years old
henry is 5 years old
susan is 8 years old
jenny is 12 years old

class
george is 4 years old
george is 4 years old
sam is 3 years old
mary is 89 years old
sally is 11 years old