if / else

Summary#

if / else if / else, exactly as in C#. The condition must be a bool — there is no truthiness. A string, a number or a null is not a condition, and writing one is a compile error rather than a subtle bug.

Signature#

if (<bool>) { … }
else if (<bool>) { … }
else { … }

Description#

How do I write an if / else chain?#

string Band(decimal total) {
  if (total >= 1000m) {
    return "large";
  } else if (total >= 100m) {
    return "medium";
  } else {
    return "small";
  }
}

The condition is a bool, always#

There is no "non-empty string is true" and no "non-zero is true". Say what you mean:

entity Contact {
  [Required] string Name;
  string Phone;
}

string Reach(Contact c) {
  if (c.Phone != null) { return c.Phone; }      // not `if (c.Phone)`
  return "no phone";
}

bool IsBig(int count) {
  if (count > 0) { return true; }               // not `if (count)`
  return false;
}

This is stricter than a dynamic language, and it is the strictness that pays: if (count) and if (count > 0) mean the same thing right up until count is -1.

Choosing a value rather than a branch — ?:#

For a value rather than a branch, ?: reads better than four lines of if:

string Label(bool paid) {
  return paid ? "paid" : "outstanding";
}

Too many else ifs? — reach for switch#

A chain of else if over the same value is usually a switch — especially over an enum, where the compiler can then tell you when you have missed a case.

See also#

• switch — branching over many values of one expression
• enum — the closed sets a switch is exhaustive over
• while — repeating while a condition holds