Question

我是C ++的新手，我确实需要一些帮助。我正在尝试创建一种结构以与GSL蒙特卡洛算法对接（对于这个示例，这实际上并不重要）。我搜索了所有C ++教程，stackoverflow帖子和GSL文档，但都没有碰到运气。我正在使用armadillo软件包进行矩阵处理；它非常强大。根据文档，我无法在结构内使用动态数组，因此我试图找到一种方法来使结构变量* M指向数组* L []中的值。我确信使用向量会更好，但是1）代码的其余部分（格式错误）已经使用了指针，并且2）我将其视为学习经验。我对* M和* L []的地址在我的代码中不一样感到惊讶。同样不那么重要的是，我对我的std :: cout为每行打印不同数量的空格感到惊讶。代码将在打印最后一个std :: cout之前退出，如下面的输出所示。

感谢您的帮助！

#include "pch.h"
#include "stdio.h"
#include "complex"
#include "new"
#include "armadillo"
using namespace arma;

class Link
{
public:

    arma::Mat<cx_double>::fixed<3, 3>* dir[4];                                      // pointer to directional SU(3) matrices

    Link();                                                                         // default constructor

};

Link::Link()                                                                        // default constructor - all directional matrices are the identity 
{

    for (size_t hcount = 0; hcount < 4; hcount++)
    {
        dir[hcount] = new arma::Mat<cx_double>::fixed<3, 3>{ fill::eye };           // create directional matrix in direction hcount
    }

}

struct Param
{
    Link* M;
};

int main()
{
    const int size  = 10;
    Param* Parameters = new Param{ NULL };
    Link* L[size];
    arma::Mat<cx_double>::fixed<3, 3> One{ fill::eye };


    for (size_t hcount = 0; hcount < 10; hcount++)
    {
        L[hcount] = new Link();
        *L[hcount]->dir[1] = *L[hcount]->dir[1] + hcount * One;                     // Make each array element #1 unique
    }

    Parameters->M = L[0];

    std::cout << "&L                        = " << &L << std::endl;
    std::cout << "&Parameters->M            = " << &Parameters->M << std::endl;                 // surprised that addresses are not the same
    std::cout << std::endl;

    std::cout << "&L[0]                     = " << &L[0] << std::endl;
    std::cout << "&Parameters->M[0]         = " << &Parameters->M[0] << std::endl;
    std::cout <<  std::endl;

    std::cout << "&L[5]                     = " << &L[5] << std::endl;
    std::cout << "&Parameters->M[5]         = " << &Parameters->M[5] << std::endl;
    std::cout << std::endl;

    std::cout << "&L[5]->dir[1]             = " << &L[5]->dir[1] << std::endl;
    std::cout << "&Parameters->M[5].dir[1]  = " << &Parameters->M[5].dir[1] << std::endl;
    std::cout << std::endl;

    std::cout << "*L[5]->dir[1]             = " << *L[5]->dir[1] << std::endl;                  // This works
    std::cout << "*Parameters->M[5].dir[1]  = " << *Parameters->M[5].dir[1] << std::endl;       // This does not
    std::cout << std::endl;

}

OUTPUT
&L                                              = 0024F7CC
&Parameters->M                  = 004EEFD8

&L[0]                                           = 0024F7CC
&Parameters->M[0]                       = 004E0578

&L[5]                                           = 0024F7E0
&Parameters->M[5]                       = 004E05C8

&L[5]->dir[1]                           = 004E50C4
&Parameters->M[5].dir[1]        = 004E05CC

*L[5]->dir[1]                           =     (+6.000e+00,+0.000e+00)                      (0,0)                      (0,0)
                      (0,0)    (+6.000e+00,+0.000e+00)                      (0,0)
                      (0,0)                      (0,0)    (+6.000e+00,+0.000e+00)

*Parameters->M[5].dir[1]        =

Answer 1

java.lang.IllegalArgumentException: mandatory key is not supported by FileSystemDataInputStreamBuilder at com.google.common.base.Preconditions.checkArgument(Preconditions.java:92) at org.apache.hadoop.fs.FileSystem$FileSystemDataInputStreamBuilder.build(FileSystem.java:3650) at com.amazonaws.emr.s3select.spark.json.S3SelectJsonLineRecordReader.initialize(S3SelectJsonLineRecordReader.java:79) at com.amazonaws.emr.s3select.spark.json.JsonS3SelectFileLinesReader.<init>(JsonS3SelectFileLinesReader.scala:59) at com.amazonaws.emr.s3select.spark.json.JsonS3SelectDataSource.readFile(JsonS3SelectDataSource.scala:56) at com.amazonaws.emr.s3select.spark.json.JsonS3SelectFileFormat$$anonfun$buildReader$2.apply(JsonS3SelectFileFormat.scala:106) at com.amazonaws.emr.s3select.spark.json.JsonS3SelectFileFormat$$anonfun$buildReader$2.apply(JsonS3SelectFileFormat.scala:104) at org.apache.spark.sql.execution.datasources.FileFormat$$anon$1.apply(FileFormat.scala:148) at org.apache.spark.sql.execution.datasources.FileFormat$$anon$1.apply(FileFormat.scala:132) at org.apache.spark.sql.execution.datasources.FileScanRDD$$anon$1.org$apache$spark$sql$execution$datasources$FileScanRDD$$anon$$readCurrentFile(FileScanRDD.scala:124) at org.apache.spark.sql.execution.datasources.FileScanRDD$$anon$1.nextIterator(FileScanRDD.scala:177) at org.apache.spark.sql.execution.datasources.FileScanRDD$$anon$1.hasNext(FileScanRDD.scala:101) at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage1.processNext(Unknown Source) at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43) at org.apache.spark.sql.execution.WholeStageCodegenExec$$anonfun$13$$anon$1.hasNext(WholeStageCodegenExec.scala:636) at org.apache.spark.sql.execution.datasources.FileFormatWriter$.org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask(FileFormatWriter.scala:232) at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$write$1.apply(FileFormatWriter.scala:170) at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$write$1.apply(FileFormatWriter.scala:169) at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:90) at org.apache.spark.scheduler.Task.run(Task.scala:123) at org.apache.spark.executor.Executor$TaskRunner$$anonfun$10.apply(Executor.scala:408) at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360) at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:414) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)是&L的地址，因此它是指向第一个元素的指针的地址，而不是第一个元素本身的地址。与L相同。这是& Parameters->M成员M的地址。您希望将Parameters与L[0]进行比较，除非当M不应指向Parameters->M所指的元素而是指向数组本身的开头时，则要与{{ 1}}。但是然后您还必须更改分配。

我发现使用指针数组有点奇怪。只需使用L[0]数组即可。

C ++在指向结构的指针中访问类数组指针

1 个答案: