C++ class containing arrays
I'm starting a C++ app project that basically has an object class as it's core to hold the data, then some functions will process that object's data to get the info required. I've written similar to this before in VB.net, and I've written small programs in C++ before, but that was back in Turbo C++ and didn't include creating my own class. I'd like to write this one in VC++, and I'm asking for some advice on structuring this class before I begin. When I've done similar in VB.net, I've used the approach of having structures and functions nested in a main structure. For example:
Public Structure struct_Tags Public Structure struct_TagProps Public Name As String Public Value As String End Structure Public 开发者_开发百科TagName As String Public TagProperties() As struct_TagProps Public Function HasProperties() As Boolean HasProperties = False If Not TagProperties Is Nothing Then HasProperties = True End If End Function End Structure Dim obj_Tags() As struct_Tags
This approach has worked fine in VB.net, and I dynamically redimension obj_Tags()
and obj_Tags().TagProperties()
by +1 whenever I need to within my processing loops. But my reasearch tells me that in C++ I can't have an empty array variable of the TagProperties struct in my class. Is this correct? I have no way of ever knowing what the array bounds will be in advance, so how to set this class up to have dynamically altering array bounds? By using Vector? I could have the arrays initialised with [0] bound as long as I can dynamically add dimensions to the array. Is that possible? Thanks in advance for any help.
struct struct_Tags {
struct struct_TagProps {
string Name;
string Value;
};
string TagName;
vector<struct_TagProps> TagProperties;
bool HasProperties() const {
return !TagProperties.empty().
}
};
vector<struct_Tags> obj_Tags;
To insert something:
struct_Tags newValue;
struct_Tags::struct_TagProps newProps = { "my name", "my value" };
newValue.TagProperties.push_back(newProps);
obj_Tags.push_bcak(newValue);
Depends on what kind of array you need:
If you need a dynamically allocated (variable size) array, go for a std::vector
.
If you need a more simple array, that cannot be resized, take a look at boost::array
.
The best way to create your array is to use a std::vector
. If you use the classical arrays using []
notation, you cannot resize the arrays again at runtime. You need to create a new array and copy your old array into it, then delete your old array. Anyways, it's a complicated affair, and as said by others, just use std::vector
.
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