Why string==string comparison failing?

Following is the code snippet of what I did, can some body help me where I have wrongly coded it:

#include<iostream>
using namespace std;

void modifyName(string &name)
{
    size_t sep = string::npos;
    sep = name.find_first_of(".");

    if(sep != string::npos) { name[sep] = '\0'; }
}

int main()
{
    string name("test.rtl");
    string someName("test");
    modifyName(name);

    if( someName == name ) //Failing??
        cout<<"MATCHED"<<endl;
    return 0;
}