calling function for each time for each word? duplicate?

[nickyeng]

#include <iostream>
#include <fstream>
#include <string>
#include <map>
#include <iterator>
 
using namespace std;
 
void f(string str){
    transform(str.begin(), str.end(), str.begin(), ptr_fun(::tolower));
}
 
void testFunc(){
    map<string, int> frequent;
    string str;
       string strr;
 
    while(cin >> str){
        strr = f(str);       // keep calling f(str) function in order to convert to lowercase.
        frequent[str]++;
    }
    map<string, int>::const_iterator it;
        for (it=frequent.begin(); it != frequent.end(); ++it) {
        cout << it->second << " " << it->first << endl;
    }
}
 
int main(int argc, char* argv[]){
 
    string str2;
    ifstream myfile;
 
    switch(argc){
    case 1:      // no filename specified
 
        testFunc();
        break;
 
    case 2:      // filename specified
 
        myfile.open(argv[1], ios::in);         // open the report.txt
        if(myfile.is_open()){
            while(! myfile.eof()){
                getline(myfile,str2);
            }
        }
        else{
            //cout << "Unable to open the file" << endl;
        }
        break;
    }
    return 0;
}
 

My code above, okay or not?
Is there any other simple way to convert all words user type in to lowercase by just calling the function ONCE only ?
look at the while loop in the function testFunc() ....
(try run the above program using NO command line argument, thanks)

thanks in advance.
Nicky Eng.