Question

如何将数组传递给函数，然后调用该函数以打印出数组？

我尝试使用下面的代码，但不会在控制台上显示任何内容。

struct Developer {
    address owner;
    string name;
    bytes32 namehash;
    bytes32[] skills;
    uint256[] skill_levels;
    uint wallet;
}

mapping (bytes32=>Developer) public developers_all;

function train(string _name, bytes32 _skill) public {
    bytes32 h = keccak256(abi.encodePacked(_name));

    require(developers_all[h].owner == msg.sender, "Only the owner of the developer can train them");
    require(developers_all[h].wallet >= 150, "Insufficient funds");

    uint256 i = 0; 

    do {
        if (developers_all[h].skills[i] == _skill) {
            developers_all[h].skill_levels[i]++;
        } else if ((i == (developers_all[h].skills.length - 1)) || (developers_all[h].skills.length == 0)) {
            developers_all[h].skills.push(_skill);
            developers_all[h].skill_levels.push(1);
        }
        i++;
    } while (i < developers_all[h].skills.length);

    developers_all[h].wallet = developers_all[h].wallet - 150;
}

Answer 1

i=list.length-1不是i=list。您必须为i分配数组的长度，而不是整个数组的长度

var array_list = [1,2,3,4,5, "token",6, 7, "best","life", "living"];
function printReverse(list){
  for(var i=list.length-1; i >= 0; i--){
    console.log(list[i]);
  }
}

printReverse(array_list);

Answer 2

您需要将长度作为索引值提供给i而不是数组本身。因为当您将数组与>=0进行比较时，结果为false，循环结束了。

console.log([1,2,3] >= 0)

var array_list = [1,2,3,4,5, "token",6, 7, "best","life", "living"];


function printReverse(list){
  for(var i=list.length-1; i >= 0; i--){
    console.log(list[i]);
  }
}

printReverse(array_list);

Answer 3

您需要以list.length - 1作为初始值。

function printReverse(list) {
    for (var i = list.length - 1; i >= 0; i--) {
        console.log(list[i]);
    }
}

var array_list = [1, 2, 3, 4, 5, "token", 6, 7, "best", "life", "living"];
printReverse(array_list);

一种较短的方法是获取长度并使用while语句对索引进行真实检查。

function printReverse(list) {
    var i = list.length;
    while (i--) {
        console.log(list[i]);
    }
}

var array_list = [1, 2, 3, 4, 5, "token", 6, 7, "best", "life", "living"];
printReverse(array_list);

如何将数组传递给函数，然后调用它-javascript

3 个答案: