replace multiple character in a string

As mention before, unit test is just a way to gauge my code doing the right thing. But I still miss the functional test. Take the following piece as an example:

    int seperatorPos = filename.find("/");
    if(seperatorPos > 0) {
        filename.replace(seperatorPos, 1, "_");
    }

This piece supposes to construct the index file name from the given path. For example, if the given path is path_A/path_B, then the index file name should be path_A_path_B. The unit test has done a pretty good job, but in a real world environment, the path could be path_A/path_B/path_C, in such a situation, that piece could fail. This is the drawback of unit test, it can't simulate the actual use case. To fix the defects, that piece needs to identify when it has searched through the entire string. As you guess it, I need a while loop to do this, here is the solution:

    int seperatorPos = filename.find("/");
    while( seperatorPos != string::npos ) {
        filename.replace(seperatorPos, 1, "_");
        seperatorPos = filename.find("/");
    }

Then this is the final piece that meets my requirement.