[英]How to initialize a vector in a struct in c++
I am having a problem with vectors in c++. 我在C ++中遇到向量问题。 I am new to c++ so keep this in mind please.
我是C ++的新手,所以请记住这一点。
So I have the following struct in the begining of my program: 因此,在程序开始时我具有以下结构:
typedef struct grupo
{
float transX, transY, transZ, rotX, rotY, rotZ, rotAngle, scaleX, scaleY, scaleZ;
char **modelos;
struct grupo** grupos;
int nNomes = 0, nGrupos=0;
std::vector<float> vertices;
};
struct grupo *grupo;
And I just start the main like this: 我只是这样开始主程序:
grupo = (struct grupo*)malloc(sizeof(struct grupo));
grupo->modelos = (char **)malloc(sizeof(1));
grupo->grupos = (struct grupo **)malloc(sizeof(struct grupo));
And in the middle of main I am tryting to use this: 在main的中间,我尝试使用它:
grupo->vertices.push_back(x);
But it keeps crashing the program. 但是它总是使程序崩溃。 I am using visual studio, and using debugging mode.
我正在使用Visual Studio,并使用调试模式。 I can see that is when pushing X to the vector that crashes (x has a value).
我可以看到,这是当将X推到崩溃的向量上时(x有一个值)。 I've tried to change the vector to an array of floats.
我试图将向量更改为浮点数数组。 So the problem i can imagine is with the initialization of the vector... Can you help with what am I missing?
所以我可以想象的问题是向量的初始化...您能帮我解决一下吗?
Thank you :) 谢谢 :)
You're using C++, you don't need the "new" or malloc keyword unless for specific reasons. 您使用的是C ++,除非出于特殊原因,否则不需要“ new”或malloc关键字。 You don't need the typedef for structs.
您不需要为结构体使用typedef。
I'm not sure what your char** is supposed to be, but you can use std::string for strings. 我不确定您的char **应该是什么,但是您可以将std :: string用于字符串。
Maybe what you're trying to do is this: 也许您想要做的是这样的:
struct Grupo
{
float transX, transY, transZ, rotX, rotY, rotZ, rotAngle, scaleX, scaleY, scaleZ;
std::string modelos;
int nNomes = 0, nGrupos=0;
std::vector<float> vertices;
};
In main: 在主要方面:
Grupo grupo;
grupo.vertices.push_back( ... );
Then I would advise you to read a bit more about what is exactly the C++ language and how it's not C. 然后,我建议您多读一些关于什么是C ++语言以及它不是C语言的更多信息。
Since you're using C++; 由于您使用的是C ++; if you want to create a
grupo
dynamically, you should use the new
operator, with the constructor: 如果你想创建一个
grupo
动态,您应该使用new
运营商,拥有的构造器:
grupo = new grupo();
malloc
does not properly initialize C++ objects such as std::vector
. malloc
不能正确初始化C ++对象,例如std::vector
。
PS I am not sure what the grupo->modelos
and grupo->grupos
are supposed to be, but I'd use proper C++ types for them (perhaps modelos
should be std::string
, etc). PS我不确定
grupo->modelos
和grupo->grupos
应该是什么,但是我会为它们使用适当的C ++类型(也许modelos
应该是std::string
等)。 Additionally, I suspect that you've got one *
too much for both modelos
and grupos
. 此外,我怀疑你有一个
*
吃不消都modelos
和grupos
。
C++ does not need the typedef in the declaration. C ++在声明中不需要typedef。
To properly initialize a structure, you should write a ctor to replace the compiler provided ctor (which generally does nothing). 要正确初始化结构,您应该编写一个ctor来替换编译器提供的ctor(通常不执行任何操作)。
Something like the following (with just a few attributes): 类似于以下内容(仅带有一些属性):
struct grupo
{
float transX, transY;
// ...
int nNomes;
int nGrupos;
std::vector<float> vertices;
// I prefer initialization list form
grupo() : transX(0.0),
transY(1.0),
// ...
nNomes(0),
nGrupos(0)
// vertices default ctor is ok, creates empty vector
{
// use vertices.push_back(...); to fill vertices
}
};
grupo grupo;
Next you will want to write a more useful ctor, one with parameters to use (instead of the literal constants), such that you could build multiple grupo. 接下来,您将要编写一个更有用的ctor,一个带有要使用的参数(而不是文字常量)的ctor,以便您可以构建多个grupo。
grupo grupo1(1.0, 2.0, 3, 4);
grupo grupo2(3.0, 4.0, 5, 6);
// etc.
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