[PHP知识库]PHP函数array_sum

array_sum计算数组元素的和。

• 如果元素的值都是整数，则返回整数结果
• 如果元素的值有浮点数，则返回浮点数结果
• false，null被转换成 0
• true转成1
• 数组和对象被忽略不参与计算
• 资源句柄被转换成相应的整型值
• 字符串被转成相应的数字，不能转换的跳过

/**
 * Calculate the sum of values in an array
 * @link https://php.net/manual/en/function.array-sum.php
 * @param array $array <p>
 * The input array.
 * </p>
 * @return int|float the sum of values as an integer or float.
 */
function array_sum(array $array) { }

示例：注意看下面的结果，结合上面的几条结论

$fp = fopen(__DIR__.'/order.php', 'r');

var_dump($fp); //resource(5) of type (stream)

$array = [
    true,     //1
    false,    //0
    null,     //0
    $fp,      //5
    2.5,     //2.5
    [],
    'a',
    '3',     //3
    new \stdClass()
];

$result = array_sum($array);

var_dump($result);
//结果
//double(11.5)

?扩展阅读：

array_sum函数C源码实现

PHP_FUNCTION(array_sum)
{
	zval *input,
		 *entry,
		 entry_n;

	ZEND_PARSE_PARAMETERS_START(1, 1)
		Z_PARAM_ARRAY(input)
	ZEND_PARSE_PARAMETERS_END();

	ZVAL_LONG(return_value, 0);

	ZEND_HASH_FOREACH_VAL(Z_ARRVAL_P(input), entry) {
		if (Z_TYPE_P(entry) == IS_ARRAY || Z_TYPE_P(entry) == IS_OBJECT) {
			continue;
		}
		ZVAL_COPY(&entry_n, entry);
		convert_scalar_to_number(&entry_n);
		fast_add_function(return_value, return_value, &entry_n);
	} ZEND_HASH_FOREACH_END();
}

数组元素中的数据转换成标量数据实现?

static void ZEND_FASTCALL _convert_scalar_to_number(zval *op, zend_bool silent, zend_bool check) /* {{{ */
{
try_again:
	switch (Z_TYPE_P(op)) {
		case IS_REFERENCE:
			zend_unwrap_reference(op);
			goto try_again;
		case IS_STRING:
			{
				zend_string *str;

				str = Z_STR_P(op);
				if ((Z_TYPE_INFO_P(op)=is_numeric_string(ZSTR_VAL(str), ZSTR_LEN(str), &Z_LVAL_P(op), &Z_DVAL_P(op), silent ? 1 : -1)) == 0) {
					ZVAL_LONG(op, 0);
					if (!silent) {
						zend_error(E_WARNING, "A non-numeric value encountered");
					}
				}
				zend_string_release_ex(str, 0);
				break;
			}
		case IS_NULL:
		case IS_FALSE:
			ZVAL_LONG(op, 0);
			break;
		case IS_TRUE:
			ZVAL_LONG(op, 1);
			break;
		case IS_RESOURCE:
			{
				zend_long l = Z_RES_HANDLE_P(op);
				zval_ptr_dtor(op);
				ZVAL_LONG(op, l);
			}
			break;
		case IS_OBJECT:
			{
				zval dst;

				convert_object_to_type(op, &dst, _IS_NUMBER, convert_scalar_to_number);
				if (check && UNEXPECTED(EG(exception))) {
					return;
				}
				zval_ptr_dtor(op);

				if (Z_TYPE(dst) == IS_LONG || Z_TYPE(dst) == IS_DOUBLE) {
					ZVAL_COPY_VALUE(op, &dst);
				} else {
					ZVAL_LONG(op, 1);
				}
			}
			break;
	}
}