结构体返回错误-C
这个程序是用 C 编写的，
它应该得到一个两个 D 数组（matrixAdd）并用 scanMtx 扫描它（扫描函数不在这里，因为代码不相关）
问题：EDMtx 函数返回扫描矩阵 1， 1,1,,1,-8,1,,1,1,1 当它返回到 main 时，它是： 0,0,0,0,0,0,junk,junk,junk
似乎有一个地址错误
我做错了什么？
#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
struct matrix
{
int* ptr;
int row;
int column;
};
matrix EDMtx();
void main( int argc, char* argv[])
{
int matrixAdd[5][5]={{1,1,1,3,4},{1,1,1,3,4},{1,1,1,3,4},{1,1,1,3,4},{1,1,1,3,4}};
matrix mtx;
matrix scanMtx;
mtx.ptr=&matrixAdd[0][0];
mtx.row=5;
mtx.column=5;
scanMtx= EDMtx();
// mtx= ScanM(mtx,1,1,scanMtx);- doesn't important to you.
getchar();
}
matrix EDMtx()
{
int matrx[3][3]={{1,1,1},{1,-8,1},{1,1,1}};
matrix Mtx;
Mtx.ptr=&matrx[0][0];
Mtx.row=3;
Mtx.column=3;
return Mtx;
}
this program is written in C
it supposed to get a two D array( matrixAdd) and scan it with scanMtx (the scanning function isn't here becuase the code isn't relevant)
the problem: the EDMtx function return the scanning matrix 1,1,1,,1,-8,1,,1,1,1
when it return back to main it is : 0,0,0,0,0,0,junk,junk,junk
it seems that there is a address error
what did i do wrong?
#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
struct matrix
{
int* ptr;
int row;
int column;
};
matrix EDMtx();
void main( int argc, char* argv[])
{
int matrixAdd[5][5]={{1,1,1,3,4},{1,1,1,3,4},{1,1,1,3,4},{1,1,1,3,4},{1,1,1,3,4}};
matrix mtx;
matrix scanMtx;
mtx.ptr=&matrixAdd[0][0];
mtx.row=5;
mtx.column=5;
scanMtx= EDMtx();
// mtx= ScanM(mtx,1,1,scanMtx);- doesn't important to you.
getchar();
}
matrix EDMtx()
{
int matrx[3][3]={{1,1,1},{1,-8,1},{1,1,1}};
matrix Mtx;
Mtx.ptr=&matrx[0][0];
Mtx.row=3;
Mtx.column=3;
return Mtx;
}
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变量
matrixAdd和matrx以及它们指向的内存仅具有本地作用域。如果您希望它们在从函数返回后持续存在，请将它们声明为静态，或者重新设计您的代码逻辑。 （例如，通过使用malloc显式分配内存）The variables
matrixAddandmatrx, and the memory they point to, have local scope only. If you want them to persist after returning from a function, either declare themstatic, or redesign your code logic. (e.g. by usingmallocto allocate memory explicitly)在 EDMtx 中，Mtx.ptr 指向堆栈变量。这可能正在被摧毁。如果你想交换变量的指针，它们必须位于堆上
In EDMtx, Mtx.ptr is pointed to a stack variable. This is getting destroyed probably. If you want to exchange pointers to variables they must be on the heap
matrx是一个局部变量。因此，当返回EDMtx()时，它就会超出范围。并且Mtx.ptr具有局部变量matrx的引用。因此，scnMtx的指针成员在取消引用时获取垃圾值。 永远不要返回局部变量的引用。matrxis a local variable. So, it goes out of scope when upon return ofEDMtx(). And theMtx.ptrhas the reference of the local variablematrx. And so the pointer member ofscnMtx, is getting garbage values upon dereferencing. Never return references of a local variable.