Question

我的程序取了学生的姓名和年龄，这个功能应该找到最年轻，最年长的学生和平均年龄的姓名。但是，如果不打印最年轻学生的名字，谁能告诉我为什么？

void check(string *nameStudent, int *ageStudent, int num) {
    int i, young = 0, old = 0, sum = 0, mov = 0;
    string a, b;
    double average;
    for (i = 0; i < num; i++){
        if (*(ageStudent + mov) < young) {
            young = *(ageStudent + mov);
            a = *(nameStudent + mov);
        }
        if (*(ageStudent + mov) > old) {
            old = *(ageStudent + mov);
            b = *(nameStudent + mov);
        }
        sum += *(ageStudent + mov);
        mov++;
    }
    average = (double) sum / num;
    cout << a << " Is youngest student and " << b << " Is oldest student " << endl << average << " is average age of students";
}

Answer 1

您将young初始化为0。如果学生的年龄小于young，则只会更改a和0。

不是对所有这些变量的初始值进行硬编码，而是从数组的第一个元素中获取它们。

if (num > 0) {
    young = old = sum = *ageStudent;
    a = b = *nameStudent;
}

然后，您可以将循环更改为从1而不是0开始，因为您已经处理了数组的第一个元素。

BTW，不需要mov变量，因为它始终包含与i相同的内容。请改用*(ageStudent + i)。

void check(string *nameStudent, int *ageStudent, int num) {
    int i, young = 0, old = 0, sum = 0;
    string a, b;
    double average;
    if (num > 0) {
        young = old = sum = *ageStudent;
        a = b = *nameStudent;
    }
    for (i = 1; i < num; i++){
        if (*(ageStudent + i) < young) {
            young = *(ageStudent + i);
            a = *(nameStudent + i);
        }
        if (*(ageStudent + i) > old) {
            old = *(ageStudent + i);
            b = *(nameStudent + i);
        }
        sum += *(ageStudent + i);
        mov++;
    }
    average = num ? (double) sum / num : 0; // prevent division by 0
    cout << a << " Is youngest student and " << b << " Is oldest student " << endl << average << " is average age of students";
}

Answer 2

您将最年轻学生的年龄保持在`<html> <head> <title></title> <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.6/angular.min.js"></script> <script type="text/javascript" src="/../../Scripts/angularsample.js"></script> </head> <body ng-app="spiceApp"> <div> <div ng-controller="SpicyController"> <p> lets try some code by using service </p> <input ng-init="message='Girish'" ng-model="message" /> <button ng-click="notify(message);">Notify{{1+2}}</button> <p>alert will display only by clicking three times.</p> </div> <div ng-controller="List"> <button ng-click="bringList()">getList</button> <table> <tr ng-repeat="app in appslist"> <td> {{app.Name}} </td> </tr> </table> </div> </div> </body> </html>`，但将其初始化为var myApp = angular.module('spiceApp', []); myApp.controller('SpicyController', ['$scope', '$http', 'userService', , function ($scope, $http, userService) { //below code is using sservice $scope.notify = function (msg) { userService(msg); }; }]); myApp.controller('List', ['$scope', 'getList', function ($scope, getList) { $scope.bringList = function () { getList.getAppsList().then(function (list) { $scope.appslist = list; }); }; }]); myApp.factory('getList', ['$http',function ($http) { //this code for getting list from controller. return getList.getAppsList=function(){ $http({ method: 'GET', url: 'Home/GetAppsList' }) .success(function (response) { return response.data; }, function (error) { console.log(error); }); } }]); myApp.factory('userService', ['$window', function (win) { var msgs = []; return function (msg) { msgs.push(msg); if (msgs.length == 3) { win.alert(msgs.join('\n')); msgs = []; } }; }]);`，因此列表中的所有学生都不会满足young。将其初始化为较大的值。通常，所讨论的类型（0）可以采用的最大值是首选。如果这对您来说听起来很复杂，那么在这种情况下您可以使用类似ageStudent[i] < young的内容，只要您的学生都不会超过一千年。

Answer 3

将初始年龄设置为最大整数以强制进行设置 a 的比较。

严格来说，最初的旧应该是负的最大（有符号）整数来处理所有正式可能的情况，并且还应该解决 num = 0的情况。

Answer 4

您的问题是变量young。您在此处将其初始化为0：

int i, young = 0, old = 0, sum = 0, mov = 0;

然后你在这里查看：

if (*(ageStudent + mov) < young) {

但是ageStudent变量将始终大于0，只要您的学生中没有人不到0岁，因此条件将始终评估为false。

您可以通过在函数开头将年轻人设置为高数字来解决问题。

为什么我的程序不打印字符串？

4 个答案: