Question

I asked a similar question but left out an important detail. I am doing some text processing on an array of chars (cstring). The input array is copied to the output array except certain characters get changed (e.g. a->b). This is done by using a switch statements. What I want is if two or more of a certain characters are found in a row only one of them gets copied to the new array (so I wouldn’t want two spaces in a row).

This is what I’ve got so far and it works without skipping the two or more in a row of certain characters:

char cleanName[ent->d_namlen];
    for(int i = 0; i < ent->d_namlen; i++)
    {
        switch(ent->d_name[i])
        {

            case 'a' :
                cleanName[i] = 'b';//replace a's with b's (just an example)
                break;
            case ' ' ://fall through
            case '-' :
            case '–' :
            case '—' :
                cleanName[i] = '_';//replace spaces and dashes with spaces
                break;
            ....//more case statments
           default: 
                cleanName[i] = ent->d_name[i];
  }
}

For example if two characters in a row get replaced by underscores, how do I do this? Would I only execute the switch statement if(ent->d_name[i] != previous || (ent->d_name[i] != '-' && ent->d_name[i] != '_' && ent->d_name[i] != ' ')

This may be more of an algorithm question than an implementation specific one.

Example input: abbc–d-e
Output: bbbc_d_e
(for simplicity sake assume ‘a’ is mapped to ‘b’ but really there is more than this)

Answer 1

Easiest would be to use std::unique with a custom predicate, after your existing transformation:

cleanName.erase(std::unique(std::begin(cleanName), std::end(cleanName),
    [](char c, char d) { return c == '_' && d == '_'; }), std::end(cleanName));

For a char array:

length = std::unique(cleanName, &cleanName[length],
    [](char c, char d) { return c == '_' && d == '_'; }) - cleanName;
cleanName[length] = '\0';