我在vba中访问字典中的项目时遇到了问题。
我有以下字典：
Dim CResults as dictionary
我添加了项目：
CResults.add currentkey, result
Currentkey是我自己从名为DCRkey
Private loadcase as long
Private csystem as String
Private node as long
和result是名为DCR的类中的另一个对象：
Private Fs as double
Private C1 as double
Private C2 as double
...
然后我尝试使用
访问某个项目Dim accesskey as DCRKey
accesskey.loadcase=10
accesskey.node = 2000
accesskey.csystem="Global"
Sheets("Results").cells(i,1).value= CResults(accesskey).C1
这就是我收到错误的地方：runtime error 424 object required
然后我想也许我搜索的键和项目没有导入，所以我决定在excel工作表上显示我的整个字典：
Dim testkey as variant
dim i as integer
i=1
with worksheet("Test")
For each testkey in CResults.keys
.cells(i,1)=test.node
.cells(i,2)=test.loadcase
.cells(i,3)=test.csystem
.cells(i,4)=Cresults(testkey).C1
.cells(i,5)=Cresults(testkey).Fs
if accesskey.loadcase=testkey.loadcase and accesskey.node=testkey.node and accesskey.csystem=testkey.csystem then
Msgbox "This key is the same as the accesskey"
End if
i=i+1
Next
End with
我看到的是：
"This key is the same as the acceskey"显示一次for each循环访问字典中的项目是有效的，因为C1和Fs在工作表上正确显示然后我想也许是因为testkey被定义为变体而不是DCRKey，所以我试过了：
dim a as variant
Set a = currentkey
.Cells(i,1) = CResults(a).C1
但它不起作用，我仍然得到了runtime error 424。
我也尝试过：
CResults.exists(accesskey)
它返回false并在字典中创建一个新条目（顺便提一下，当它这样做时），使用与acceskey相同的键和一个空项。
所以我的问题是：为什么使用自定义类型键访问项目在for each循环中工作而不是在独立调用中。我错过了什么？这段代码与我编写的代码非常相似但不完全相同（为了让您更好地理解）。如果您认为真正的代码可以提供帮助，请告诉我。
谢谢你的帮助。
答案 0 :(得分：5)
您需要记住，类的两个实例不是同一个，即使它们的所有属性都设置为相同的值。
让我们考虑以下示例：
#include <iostream>
#include <stdio.h>
using namespace std;
class FlyingMode {
protected:
float time, fuel_rate, start, end, pace, distance;
float total;
public:
FlyingMode(float a=0, float b=0, float c=0,
float d=0, float e=0, float f=0){
time = a;
fuel_rate = b;
start = c;
end = d;
pace = e;
distance = f;
total = 0;
}
virtual int calcFuel(){
return 0;
}
};
class Holding: public FlyingMode{
public:
Holding(float a=0, float b=0, float c=0,
float d=0, float e=0, float f=0):FlyingMode(a, b, c, d, e, f) { }
int calcFuel(){
total = (time * fuel_rate * 60);
return total;
}
};
class Raising: public FlyingMode{
public:
Raising(float a=0, float b=0, float c=0,
float d=0, float e=0, float f=0):FlyingMode(a, b, c, d, e, f) { }
int calcFuel (){
if(start < end && pace != 0 ){
total = (end - start)/pace * fuel_rate;
return (end - start)/pace * fuel_rate;
}else{
return 0;
}
}
};
class Landing: public FlyingMode{
public:
Landing(float a=0, float b=0, float c=0,
float d=0, float e=0, float f=0):FlyingMode(a, b, c, d, e, f) { }
int calcFuel (){
if(start > end && pace != 0 ){
total = (start - end)/pace * fuel_rate;
return (start - end)/pace * fuel_rate;
}else{
return 0;
}
}
};
class Straight: public FlyingMode{
public:
Straight(float a=0, float b=0, float c=0,
float d=0, float e=0, float f=0):FlyingMode(a, b, c, d, e, f) { }
int calcFuel (){
if(distance != 0 || pace != 0 ){
total = distance/pace * fuel_rate;
return distance/pace * fuel_rate;
}else{
return 0;
}
}
};
// Main function for the program
int main( ){
float a=0, b=0;
float c=0, d=0, e=0, f=0;
float total = 0;
char op;
Holding hold;
Raising raise;
Landing land;
Straight straight;
while(op != 'x') {
cout << "Enter the move : " << endl;
cout << "1 ---> Holding Flight" << endl;
cout << "2 ---> Raising" << endl;
cout << "3 ---> Landing " << endl;
cout << "4 ---> Straight Flight " << endl;
cout << "5 ---> Calculate fuel" << endl;
cout << "x ---> Exit " << endl;
cin>>op;
cout<<"op="<<op<<endl;
if(op == '1') {
cout << "Enter time : ";
cin >> a;
cout << "Enter fuel rate: ";
cin >> b;
}
else if(op == '2') {
cout << "Enter starting altitude: ";
cin >> c;
cout << "Enter ending altitude: ";
cin >> d;
cout << "Enter raising pace: ";
cin >> e;
cout << "Enter fuel rate: ";
cin >> f;
}
else if(op == '3') {
cout << "Enter starting altitude: ";
cin >> c;
cout << "Enter ending altitude: ";
cin >> d;
cout << "Enter landing pace: ";
cin >> e;
cout << "Enter fuel rate: ";
cin >> b;
}
else if(op == '4') {
cout << "Enter ending altitude: ";
cin >> d;
cout << "Enter starting altitude: ";
cin >> c;
cout << "Enter fuel rate: ";
cin >> b;
}
else if(op == '5') {
cout <<"Total required fuel : "<< total << " kg/second "<< endl;
}
else if(op == 'x') {
cout << "System will exit..." << endl;
return 0;
}
else {
//if(op==(1|2|3|4|5)){}
//else cout << "Wrong selection." << endl;
continue;
}
FlyingMode *mode;
hold = Holding(a, b, 0, 0, 0, 0);
raise = Raising(0, f, c, d, e, 0);
land = Landing(0, b, d, c, e, 0);
straight = Straight(0, b, c, d, 0, 0);
//store holding address
//call holding fuel
mode = &hold;
float hold_result = mode -> calcFuel();
//call raising fuel
mode = &raise;
float raise_result = mode -> calcFuel();
//call landing fuel
mode = &land;
float land_result = mode -> calcFuel();
//call straight fuel
mode = &straight;
float str_result = mode -> calcFuel();
//calculate total
/*cout << "hold_result" << hold_result;
cout << "raise_result" << raise_result;
cout << "land_result" << land_result;
cout << "str_result" << str_result;*/
total = total+hold_result + raise_result + land_result + str_result;
cout <<"Total required fuel : "<< total << " kg/second "<< endl;
}
return 0;
}
在此示例中，Sub compareSimilarObjects()
Dim key1 As DCRKey
Dim key2 As DCRKey
Set key1 = New DCRKey
With key1
.loadcase = 10
.node = 2000
.csystem = "Global"
End With
Set key2 = New DCRKey
With key1
.loadcase = 10
.node = 2000
.csystem = "Global"
End With
'Debug.Print to check pointer assigne to those variables.
Debug.Print "Key1: " & ObjPtr(key1)
Debug.Print "Key2: " & ObjPtr(key2)
End Sub
类的两个对象都将所有属性设置为相同的值。但是，它们与下面的代码在最后运行DCRKey后看到的对象不同。
在那些Debug.Prints中使用了VBA内置函数Debug.Print。此函数的目的是返回指向给定对象的指针。对象的每个实例都有自己唯一的指针，因此如果下面的代码打印了两个不同的指针，则表示这些对象不相同。
现在，让我们考虑另一个例子：
ObjPtr在这里，我们为变量Sub compareSimilarObjects()
Dim key1 As DCRKey
Dim key2 As DCRKey
Set key1 = New DCRKey
With key1
.loadcase = 10
.node = 2000
.csystem = "Global"
End With
Set key2 = key1
'Debug.Print to check pointer assigned to those variables.
Debug.Print "Key1: " & ObjPtr(key1)
Debug.Print "Key2: " & ObjPtr(key2)
'Now those pointers should be the same.
End Sub
分配了一个新的类DCRKey实例，然后我们将相同的对象分配给变量key1。现在key2应该为ObjPtr和key1返回相同的值，因为这是同一个对象，它只是分配给两个不同的变量。
现在，让我们回到字典。
字典搜索key2类型键的方式是指针。
因此，如果要在字典中找到一个以对象作为键添加的条目，则需要使用完全相同的对象（而不是具有相同属性的对象）。
示例：
Object