Improving PHP function efficiency: from principle to application

PHP function efficiency improvement: avoid unnecessary copying or calculations; use local variables instead of passing parameters; cache expensive operations. Practical case: String processing function optimization: use string buffer; use preg_replace instead of str_replace; avoid unnecessary string conversion.

PHP function efficiency improvement: principles and applications

Principles of optimizing function calls

1. Avoid unnecessary copying or calculation
Do not repeatedly calculate or copy variable values ​​inside the function. For example:

function calculate($a, $b) {
  $sum = $a + $b;
  $product = $a * $b;
  return $sum + $product;
}

Improvement:

function calculate($a, $b) {
  $sum = $a + $b;
  return $sum + ($a * $b);
}

2. Use local variables instead of passing parameters
When the passed parameters are used inside the function, PHP will copy them . Therefore, declare frequently accessed parameters as local variables to avoid extra copies:

function myFunction($input) {
  $result = '';
  for ($i = 0; $i < count($input); $i++) {
    $result .= $input[$i];
  }
  return $result;
}

Improvement:

function myFunction($input) {
  $count = count($input);
  $result = '';
  for ($i = 0; $i < $count; $i++) {
    $result .= $input[$i];
  }
  return $result;
}

3. Cache expensive operations
if function Perform expensive operations, such as database queries or complex calculations, and cache the results to avoid repeating those operations.

function getFromDB($id) {
  static $cache = [];
  if (!isset($cache[$id])) {
    $cache[$id] = queryDB($id);
  }
  return $cache[$id];
}

Practical case: Improving the efficiency of string processing functions

1. Using string buffer
PHP’s string buffer Provides faster string processing than string concatenation. The following is an example of using a string buffer:

$string = 'Hello';
$string .= ' World'; // 字符串拼接

$buffer = new StringWriter();
$buffer->write('Hello');
$buffer->write(' World'); // 字符串缓冲区
$string = $buffer->toString();

2. Use preg_replace instead of str_replace
preg_replace Faster than str_replace for more complex replacements. The following is an example of preg_replace:

$string = preg_replace('/<br>/', "\n", $string); // `preg_replace`

$string = str_replace('<br>', "\n", $string); // `str_replace`

3. Avoid unnecessary string conversions
Use numbers or booleans directly as strings instead Convert it to a string first:

echo 'Value: ' . 123; // 直接使用数字

echo 'Value: ' . (string) 123; // 转换为字符串

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