[英]C++ Array of struct initialization
I am not really used to coding in C++ and this probably is a simple issue that I am not able to get the correct syntax of. 我不太习惯用C ++进行编码,这可能是一个简单的问题,我无法获得正确的语法。
What I am basically trying to achieve is that, from one method where I declare an array of a struct (size not specified), I call a method where I pass this array. 我基本上想要实现的是,从一个我声明一个结构数组(未指定大小)的方法中,我调用一个传递此数组的方法。 The method should initialize the values of the array. 该方法应初始化数组的值。 I tried to get a simple code working but getting errors. 我试图使一个简单的代码正常工作,但出现错误。 The following piece of code gives me a compilation error. 下面的代码给了我一个编译错误。 Can someone point out how to achieve this? 有人可以指出如何实现这一目标吗?
struct ABC
{
int a;
int b;
};
void test(ABC * a)
{
a[] = {{2,3},{4,5}};
}
int main() {
ABC arr[2];
test(arr);
}
EDIT: 编辑:
The following works, but I would like the initialization to work in one line. 下面的作品,但我希望初始化工作在一行中。
struct ABC
{
int a;
int b;
};
void test(ABC *a)
{
a[0].a = 2;
a[0].b = 3;
a[1].a = 4;
a[1].b = 5;
}
int main() {
ABC arr[2];
test(arr);
}
You could use a setup like this, making use of the C++ standard library. 您可以使用C ++标准库这样的设置。 Compile it with the -std=c++11
flag to allow for the initialization I did in the push_back
: 使用-std=c++11
标志对其进行编译,以允许我在push_back
进行的初始化:
#include <vector>
#include <iostream>
struct ABC
{
int a;
int b;
};
void test(std::vector<ABC>& a)
{
a.push_back({2,3});
a.push_back({4,5});
}
int main()
{
std::vector<ABC> arr;
test(arr);
// Test the outcome...
std::cout << "The size is: " << arr.size() << std::endl;
for (ABC& a : arr)
std::cout << "Element (" << a.a << "," << a.b << ")" << std::endl;
return 0;
}
Initialize each struct accessing its index in a
array. 初始化每个结构访问它的索引在a
阵列。
void test(ABC * a)
{
a[0] = {2,3};
a[1] = {4,5};
...
This way {{2,3},{4,5}};
这样{{2,3},{4,5}};
will work on initialization, ie 将在初始化上工作,即
ABC arr[2] = {
{2,3},
{4,5}
};
You have to first find out the actual size of the array and then iterate to initialize it. 您必须首先找出数组的实际大小,然后进行迭代以对其进行初始化。
Will not work, see below 无效,请参见下文
void test(ABC* a) {
int value=2;
for (int i=0;i++;i<sizeof(a)/sizeof(ABC)) {
a[i].a=value;
a[i].b=value+1;
value+=2; } }
I am not 100% sure the sizeof(a) will work in giving you the size of the array. 我不是100%确定sizeof(a)是否可以为您提供数组的大小。 If that does not work you will have to pass the size of the array as a parameter: 如果这样不起作用,则必须将数组的大小作为参数传递:
void test(ABC* a, int elements) {
int value=2;
for (int i=0;i++;i<elements) {
a[i].a=value;
a[i].b=value+1;
value+=2; } }
int main() {
ABC arr[2];
test(arr,2); }
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