不同分类的 PHP 函数的用途详解

// 获取字符串长度

$str = "Welcome to PHP!";

$len = strlen($str);

echo "Length of string: $len <br>";

// 将字符串转换为大写

$upper = strtoupper($str);

echo "String in uppercase: $upper <br>";

// 合并两个数组

$a1 = array("apple", "banana");

$a2 = array("orange", "grape");

$merged = array_merge($a1, $a2);

print_r($merged);

// 在数组中查找值

$arr = array("name" => "John", "age" => 30);

$key = array_search("John", $arr);  // 输出："name"

// 计算绝对值

$num = -10;

$abs_num = abs($num);  // 输出：10

// 将数字四舍五入到小数点后两位

$num = 3.14159;

$rounded = round($num, 2);  // 输出：3.14

// 获取当前日期和时间

$date = date('Y-m-d H:i:s');

echo "Current date and time: $date <br>";

// 日期戳转换为日期

$timestamp = 1658038400;

$date = date('d/m/Y', $timestamp);

echo "Date from timestamp: $date <br>";