PHP字符串比较在不匹配时返回true

Question

Why do the following string comparisons return true?

I am using Laravel framework 4.2, the Form::select compares the option value using this method and it's find matches that shouldn't be.

  public function testStringComparison1()
  {
    $value = '8000003E-1408739159';
    $selected = '8000010E-1434656519';
    $b = false;
    if ((string) $value == (string) $selected) {
      $b = true;
    }
    $this->assertFalse($b);  // this fails, $b == true
  }

  public function testStringComparison2()
  {
    $value = '8000008E-1408740949';
    $selected = '8000010E-1434656519';
    $b = false;
    if ((string) $value == (string) $selected) {
      $b = true;
    }
    $this->assertFalse($b);  // this fails, $b == true
  }

Answer 1

If you want to make sure the types match as well, not just the values (weird stuff with type casting), use ===.

http://php.net/manual/en/language.operators.comparison.php