我目前正在尝试创建一个地址簿应用程序，该应用程序将某些人员数据保存在一个对象中，然后将其添加到列表中。我目前正在制作一种方法来尝试在提示时列出数据，但信息没有显示，是否有人知道如何解决此问题？
namespace AddressBook
{
class Student : Person
{
public String StudentID { get; set; }
public String grade { get; set; }
public List<Student> studentList = new List<Student>();
public void addStudent(string firstName, string lastName, string address, string city, string country, string postcode, string StudentID, string grade )
{
Student student = new Student();
student.firstName = firstName;
student.lastName = lastName;
student.address = address;
student.city = city;
student.country = country;
student.postcode = postcode;
student.StudentID = StudentID;
student.grade = grade;
studentList.Add(student);
}
public void listStudentData()
{
String fname ="", lname="", add="", city="", country="", post="", id="", grd = "";
String[,] index = { { "First name: ", "Last Name: ", "Address: ", "City: ", "Country: ", "Postcode: ", "StudentID: ", "Grade: " }, { fname, lname, add, city, country, post, id, grd }, };
for (int i = 0; i < studentList.Count; i++)
{
fname = (studentList[i].firstName.ToString());
lname = (studentList[i].lastName.ToString());
add = (studentList[i].address.ToString());
city = (studentList[i].city.ToString());
country = (studentList[i].country.ToString());
post = (studentList[i].postcode.ToString());
id = (studentList[i].StudentID.ToString());
grd = (studentList[i].grade.ToString());
Console.WriteLine(index[0, i] + index[1,i]);
}
Console.WriteLine("");
}
}
}
我要打印的格式是 ＆＃34;名字：John＆＃34; ＆＃34;姓氏：史密斯＆＃34;等
但目前的格式是： ＆＃34;名字：＆＃34;
非常感谢任何建议
答案 0 :(得分：2)
你真的过于复杂化，只是为了列出学生。这很容易：
public void ListStudentData()
{
foreach (Student student in studentList)
{
Console.WriteLine("First Name: {0}", student.firstName);
Console.WriteLine("Last Name: {0}", student.lastName);
Console.WriteLine("Address: {0}", student.address);
...
...
...
}
}
此外，通常作为标准命名约定，方法名称应以大写字母开头。
答案 1 :(得分：1)
让<div class="row ng-scope" ng-repeat="field in $ctrl.getFields() as fields" ng-if="$index % 2 == 0">
<!-- ngRepeat: i in [$index, $index + 1] --><!-- ngIf: fields[i] --><nc-form-group-template ng-repeat="i in [$index, $index + 1]" ng-if="fields[i]" section-id="a1gg0000002ARlMAAW" guid="a1gg0000002ARlMAAW338C1B4330ED4993A7B3178099C70517" field="fields[i]" context-id="a38g0000001juVQAAY" ,="" enable-field-access="$ctrl.enableFieldAccess" class="ng-scope ng-isolate-scope">
<div class="form-group col-xs-6">
<nc-field-label-template section-id="a1gg0000002ARlMAAW" field="$ctrl.field" inline-help-text="" label="Other Loan Purpose" is-required="$ctrl.field.isRequired" enable-field-access="$ctrl.enableFieldAccess" class="ng-isolate-scope">
<div class="row content-label">
<div class="col-xs-12">
<span ng-show="$ctrl.inlineHelpText" popover="popover" data-toggle="popover" data-content="" class="fa fa-info-circle slds-show--inline ng-hide" data-original-title="" title="">
</span>
<label ng-bind="$ctrl.label" class="form-control-static input-sm slds-show--inline ng-binding" ng-class="{'is-required': $ctrl.isRequired, 'pull-left': $ctrl.enableFieldAccess}">Other Loan Purpose</label>
<span class="slds-p-left--medium">
<!-- ngIf: !$ctrl.field.isVisible && $ctrl.enableFieldAccess -->
<span class="slds-assistive-text">This field will be hidden from the user.</span>
</span>
<!-- ngIf: $ctrl.enableFieldAccess -->
</div>
</div>
</nc-field-label-template>
<!-- ngIf: !$ctrl.isReadOnly() --><nc-editable-field-template ng-if="!$ctrl.isReadOnly()" section-id="a1gg0000002ARlMAAW" guid="a1gg0000002ARlMAAW338C1B4330ED4993A7B3178099C70517" field="$ctrl.field" context-id="a38g0000001juVQAAY" class="ng-scope ng-isolate-scope">
<div class="row">
<div class="col-xs-12 content-body">
<nc-editable-field section-id="a1gg0000002ARlMAAW" guid="a1gg0000002ARlMAAW338C1B4330ED4993A7B3178099C70517" field="$ctrl.field" context-id="a38g0000001juVQAAY" class="ng-isolate-scope">
<!-- ngIf: $ctrl.fieldType.isTextarea($ctrl.field.fieldType, $ctrl.field.isHtmlFormatted) --><textarea ng-if="$ctrl.fieldType.isTextarea($ctrl.field.fieldType, $ctrl.field.isHtmlFormatted)" ng-model="$ctrl.field.value" ng-change="$ctrl.onChange()" ng-required="$ctrl.field.isRequired" ng-class="{
'input-sm': true,
'form-control': true,
'nc-pristine': $ctrl.getPristine(),
'nc-not-pristine': $ctrl.getNotPristine()
}" class="ng-pristine ng-valid ng-scope ng-empty input-sm form-control nc-pristine ng-valid-required ng-touched"></textarea><!-- end ngIf: $ctrl.fieldType.isTextarea($ctrl.field.fieldType, $ctrl.field.isHtmlFormatted) -->成为studentList课程的成员似乎是一种奇怪的设计选择。它属于您的程序或表单的成员。
但针对具体问题，请看这一行：
Student此时，所有这些属性变量（String[,] index = { { "First name: ", "Last Name: ", "Address: ", "City: ", "Country: ", "Postcode: ", "StudentID: ", "Grade: " }, { fname, lname, add, city, country, post, id, grd }, };
，fname等）都是空字符串。您稍后为这些变量分配值：
lname但是，这不会改变数组的内容！
我将仅使用fname = (studentList[i].firstName.ToString());
//...
变量来解释发生的事情。 fname是对内存中字符串对象的引用。最初它指的是一个空字符串。您还有fname数组，其中包含许多引用，您可以将其中一个引用设置为引用与index引用相同的空字符串对象。但是，这是该引用的副本。 fname和fname位置都指向内存中的同一对象，但它们是独立变量。现在，您为index分配一个新值。 fname变量引用内存中的不同字符串。但是，fname中的位置没有改变，仍然指的是它在开头时的空字符串。
要解决此问题，您可能想要做的是重载index类的.ToString()方法（以及Student和其他派生类）。这看起来像这样：
Person这有很多原因（其中最重要的是帮助您检查调试器中的Student对象），但是对于这个问题，它允许您重写public override string ToString()
{
return string.Format("First name: {0}\nLast Name: {1}\nAddress: {2}\nCity: {3}\nCountry: {4}\nPostcode: {5}\nStudentID: {6}\nGrade: {7}\n",
firstName,
lastName,
address,
city,
country,
postcode,
StudentID,
grade);
}
看起来像这样：
listStudentData()在一个更大，更复杂的程序中，您可能需要几种不同的方式来显示人，而不是（或除了）覆盖public void listStudentData()
{
foreach(var student in studentList)
{
Console.WriteLine(student);
}
}
之外，您将添加一个ToString()静态类，将PersonFormatter或Person转换为具有各种输出的字符串的公共方法的数量。
答案 2 :(得分：1)
注意：这不是最佳解决方案，但我只是希望您了解原始代码有什么问题，以及如果您将来发现类似问题，如何纠正错误。请参阅其他答案，了解完成任务的最有效方法。
初始化数组时，要打印的所有变量的值都是空字符串。
String fname ="", lname="", add="", city="", country="", post="", id="", grd = "";
如果要继续使用当前方法，则需要做的是使用for循环中的实际值更新变量。
像这样：
public void listStudentData()
{
String fname ="", lname="", add="", city="", country="", post="", id="", grd = "";
String[,] index = { { "First name: ", "Last Name: ", "Address: ", "City: ", "Country: ", "Postcode: ", "StudentID: ", "Grade: " }, { fname, lname, add, city, country, post, id, grd }, };
for (int i = 0; i < studentList.Count; i++)
{
index[1,0] = studentList[i].firstName.ToString();
index[1,1] = studentList[i].lastName.ToString();
index[1,2] = studentList[i].address.ToString();
index[1,3] = studentList[i].city.ToString();
index[1,4] = studentList[i].country.ToString();
index[1,5] = studentList[i].postcode.ToString();
index[1,6] = studentList[i].StudentID.ToString();
index[1,7] = studentList[i].grade.ToString();
for (int j = 0; j < 8; j++)
{
Console.WriteLine(index[0, i] + index[1,j]);
}
}
Console.WriteLine("");
}
答案 3 :(得分：1)
发布我的解决方案，您可能会发现它很有用。
我在原始示例中看到缺少基类Person类，在此处提供：
public class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string Address { get; set; }
public string City { get; set; }
public string Country { get; set; }
public string PostCode { get; set; }
public override string ToString()
{
return $"First name: {FirstName}, Last name: {LastName}, Address: {Address}, City: {City}, Country: {Country}, Post code: {PostCode}";
}
}
您可以看到我们正在重写ToString（）方法以返回预期的文字表示。正如其他人所指出的那样，在C＃（常见约定）中对公共属性使用PascalCase表示法总是更好。接下来是派生的Student类：
public class Student : Person
{
public String StudentID { get; set; }
public String Grade { get; set; }
public override string ToString()
{
return $"{base.ToString()}, Student ID: {StudentID}, Grade: {Grade}";
}
}
这里我们添加了StudentID和Grade属性，并再次覆盖了Object类的ToString（）方法。覆盖使用我们之前编写的基类的ToString（）方法。
最后，打印出一个Student对象列表的示例：
static void Main(string[] args)
{
var students = new List<Student>();
students.Add(
new Student
{
FirstName = "John",
LastName = "Doe",
Address = "43 North West",
City = "Capetown",
Country = "South Africa",
PostCode = "12345",
Grade = "A+",
StudentID = Guid.NewGuid().ToString("N")
});
foreach (Student student in students)
{
Console.WriteLine(student);
}
}
输出是：
First name: John, Last name: Doe, Address: 43 North West, City: Capetown, Country: South Africa, Post code: 12345, Student ID: 975d7bf2e80f4406b14119f8fbc3018e, Grade: A+