increment unreachable in for loop in c# method

Question

I've got this unreachable code in this for loop

public IActionResult List(int id) {
    for (id = 0; id <= 1000; id++) {
        var fil = _repoFil.GetById(id).Result;
        var listafiliali = new List<FilialeVM>();

        foreach (var filiale in fil) {
            var filialeVM = _mapper.Map<FilialeVM>(fil);
            listafiliali.Add(filialeVM);
        }

        return View(listafiliali);
    }

    return View();
}

the increment id++ is unreachable

It is unreachable because you `return View(listafiliali);` on the first iteration — Rafalon, Jun 20 '19 at 09:41
Why do you need the loop when you return the first value found? — H.G. Sandhagen, Jun 20 '19 at 09:44
Which one? It is quite unclear what you want to achieve here — Rafalon, Jun 20 '19 at 09:44
What is the *original problem*, please? What are you trying to implement? You ignore the `id` passed, you don't use `for` loop (you return from the first iteration) and you never call `return View();` — Dmitry Bychenko, Jun 20 '19 at 09:54

Dmitry Bychenko · Answer 1 · 2019-06-20T13:12:38.760

You have several problems with your code:

You ignore id passed: imagine that I call List(1234), 1234 will be ignored as well as 789 in List(789)
You don't loop over id since you return after the 1st loop
You'll never reach return View(); code: you enter loop and return from it.

I guess, you want something like this:

  using System.Linq;

  ...

  public IActionResult List(int id) {
    // for given id we collect all corresponding FilialeVM items
    var listafiliali = _repoFil
      .GetById(id)                                // items correspond to given id
      .Result
      .Select(fil => _mapper.Map<FilialeVM>(fil)) // mapped to FilialeVM
      .ToList();                                  // organized as list

    // If we have any item in listafiliali, view them, otherwise use default View()
    return listafiliali.Any()
      ? View(listafiliali)
      : View();
  }

Or if you don't want id to be passed but to scan id = [0..1000] range:

  public IActionResult List() {
    // for id in [0..1000] range we collect all corresponding FilialeVM items
    var listafiliali = Enumerable
      .Range(0, 1000 + 1)
      .SelectMany(id => _repoFil
         .GetById(id)                                 // items correspond to given id
         .Result
         .Select(fil => _mapper.Map<FilialeVM>(fil))) // mapped to FilialeVM
      .ToList();                                      // organized as list

    // If we have any item in listafiliali, view them, otherwise use default View()
    return listafiliali.Any()
      ? View(listafiliali)
      : View();
  }

score 0 · Answer 2 · answered Jun 20 '19 at 09:42

0

It is unreachable because you have this line: return View(listafiliali); in your for loop. The method returns and terminated its execution in the first for-loop iteration as soon as it hits the before mentioned return.

answered Jun 20 '19 at 09:42

Niklas7

173
8

score 0 · Accepted Answer · answered Jun 20 '19 at 09:49

return your View AFTER your loop finished

public IActionResult List(int id) {
    var listafiliali = new List<FilialeVM>();

    for (id = 0; id <= 1000; id++) {
        var fil = _repoFil.GetById(id).Result;            
        foreach (var filiale in fil) {
            var filialeVM = _mapper.Map<FilialeVM>(fil);
            listafiliali.Add(filialeVM);
        }            
    }

    if(listafiliali.Count > 0)
       return View(listafiliali);

    return View();
}

increment unreachable in for loop in c# method

3 Answers3