array explode ( string $delimiter, string $string, [ , $limit ] )

$str = 'hello,world,heiheihei,php';

$arr = explode(',', $str);
print_r($arr);

$arr = explode(',', $str, 1);
print_r($arr);

$arr = explode(',', $str, -1);
print_r($arr);

$arr = explode(',', $str, 0);
print_r($arr);

if (p2 == NULL) {
        // 找不到分隔符，直接返回整个字符串
    add_next_index_stringl(return_value, p1, Z_STRLEN_P(str), 1);
} else {
    do {
        // 将p1添加到return_value数组中
        add_next_index_stringl(return_value, p1, p2 - p1, 1);
        p1 = p2 + Z_STRLEN_P(delim);
    } while ((p2 = php_memnstr(p1, Z_STRVAL_P(delim), Z_STRLEN_P(delim), endp)) != NULL &&
             --limit > 1);

    // 将最后一个值添加到return_value
    if (p1 <= endp)
        add_next_index_stringl(return_value, p1, endp-p1, 1);
}

string implode ( string $glue, array $pieces )
string implode ( array $pieces )

$arr = array('hello', 'world');

$str = implode('-‘, $arr);// 输出"hello-world"

$str = implode($arr); // 输出"helloworld"
$str = implode($arr, '-'); // 输出"hello-world"

// 遍历数组的每一个元素，判断其类型，然后调用smart_str_appendl函数将值追加到字符串中
    while (zend_hash_get_current_data_ex(Z_ARRVAL_P(arr), (void **) &tmp, &pos) == SUCCESS) {
        switch ((*tmp)->type) {
            case IS_STRING:
                smart_str_appendl(&implstr, Z_STRVAL_PP(tmp), Z_STRLEN_PP(tmp));
                break;

            case IS_LONG: {
                char stmp[MAX_LENGTH_OF_LONG + 1];
                str_len = slprintf(stmp, sizeof(stmp), "%ld", Z_LVAL_PP(tmp));
                smart_str_appendl(&implstr, stmp, str_len);
            }
                break;

            case IS_BOOL:
                if (Z_LVAL_PP(tmp) == 1) {
                    smart_str_appendl(&implstr, "1", sizeof("1")-1);
                }
                break;

            case IS_NULL:
                break;

            case IS_DOUBLE: {
                char *stmp;
                str_len = spprintf(&stmp, 0, "%.*G", (int) EG(precision), Z_DVAL_PP(tmp));
                smart_str_appendl(&implstr, stmp, str_len);
                efree(stmp);
            }
                break;

            case IS_OBJECT: {
                int copy;
                zval expr;
                zend_make_printable_zval(*tmp, &expr, &copy);
                smart_str_appendl(&implstr, Z_STRVAL(expr), Z_STRLEN(expr));
                if (copy) {
                    zval_dtor(&expr);
                }
            }
                break;

            default:
                tmp_val = **tmp;
                zval_copy_ctor(&tmp_val);
                convert_to_string(&tmp_val);
                smart_str_appendl(&implstr, Z_STRVAL(tmp_val), Z_STRLEN(tmp_val));
                zval_dtor(&tmp_val);
                break;

        }

        // 添加glue字符
        if (++i != numelems) {
            smart_str_appendl(&implstr, Z_STRVAL_P(delim), Z_STRLEN_P(delim));
        }
        zend_hash_move_forward_ex(Z_ARRVAL_P(arr), &pos);
    }
    // 在尾部添加结束字符0
    smart_str_0(&implstr);