list中有n个值,赋值给k个变量:a1, a2, ……,ak n = k时:a1, a2, ……,ak = list n > k时:使用1式报错:ValueError: too many values to unpack n < k时:使用1式报错:ValueError: need more than "n" values to unpack 只有n >= k时才可赋值: 从下标i开始的k个元素赋给a1, a2, ..., ak: a1, a2, ..., ak =
The problem here is that you've defined an anonymous method which returns a string but are trying to assign it directly to a string. It's an expression which when invoked produces a string it's not directly a string. It needs to be assigned to a comp
经常需要将一个字符串分割成一组值,然后赋值给不同的变量. 逐行赋值非常繁琐,于是查了一下 PHP 中是否有类似 python 中 a, b = (a, b) 的操作. 果然有 $info = array('coffee', 'brown', 'caffeine'); list($drink, $color, $power) = $info; echo "$drink is $color and $power makes it special.\n"; list 这个关键字,是专门为这个
2012-03-25 12:12 a786013819 | 分类:数据库DB | 浏览1393次 $sql = "select field1 from pre_common_member_profile where uid='$username'";得到的结果是这样的:field11234怎么把1234赋值给变量 你是只取这一个值还是要取数组.只取一个的话.$sql = "select field1 from pre_common_member_profile where u
if (!("a" in window)) { var a = 1; } alert(a); 结果:undefined 分析: 首先,所有的全局变量都是window的属性,语句 var a = 1;等价于window.a = 1: 第二,所有的变量声明都在范围作用域的顶部,如: alert("a" in window); var a; 相当于: var a; alert("a" in window); 这是因为JavaScript引擎首先会扫墓所