「PHP7数组详解」：第1章 （四）基本运算符和逻辑操作符

  /**   * ------------------------------------------------   * 下面是运算和赋值操作   * ------------------------------------------------    */  $a = 1.542e-4;  $b = pow(2,5);  echo "a = " . $a . ", b = " . $b, "<br/>";    $b += 0.54;  echo "b = " . $b, "<br/>";  $b -= 7.5;  echo "b = " . $b, "<br/>";  $b *= mt_rand(1,10);  echo "b = " . $b, "<br/>";  $b /= 5;  echo "b = " . $b, "<br/>";  $b %= 3;  echo "b = " . $b, "<br/>";  // 自动转换为字符串  $b .= " - toString";  echo "b = " . $b, "<br/>";

  /**   * ------------------------------------------------   * 下面是逻辑操作符   * ------------------------------------------------    */  $a = 65;  $b = 47;  if ($a == $b) echo "a等于b", "<br/>";  if ($a != $b) echo "a不等于b", "<br/>";  if ($a === $b) echo "a全等于b", "<br/>";  if ($a !== $b) echo "a不全等于b", "<br/>";  if ($a <> $b) echo "a不等于b", "<br/>";  if ($a > $b) echo "a大于b", "<br/>";  if ($a < $b) echo "a小于b", "<br/>";  if ($a >= $b) echo "a大于等于b", "<br/>";  if ($a <= $b) echo "a小于等于b", "<br/>";  // 还有一个重量级的，太空船操作符  // 左边 > 右边，返回 1  // 左边 = 右边，返回 0  // 左边 < 右边，返回 -1  switch ($a <=> $b) {    case 1:      echo "a大于b", "<br/>";      break;    case 0:      echo "a等于b", "<br/>";      break;    case -1:      echo "a小于b", "<br/>";      break;  }