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POError while freeing memory
 

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  1. POError while freeing memory
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    <p>These are the files:</p> <pre><code>//============================================================================ // Name : linearMatrix.hpp // Author : Flores, Facundo Gabriel // Version : 0.1 // Description : This file contains the linearMatrix class. //=========================================================================== #ifndef LINEARMATRIX_HPP_ #define LINEARMATRIX_HPP_ class linearMatrix { public: //Constructor linearMatrix(const int Width, const int Heigth); //Destructor ~linearMatrix(); //We read a matrix file void Read_File_Matrix(const char *Path); //We write a matrix file void Write_File_Matrix(const char *Path); //Generate a diagonal dominant matrix void Generate_Diagonal_Dominant(void); //Generate a random matrix void Generate_Random_Matrix(void); //Copy a float *vector void Copy_Vector(const float *V, const int Width, const int Heigth); //Show a little vector void Show_Little_Matrix(void); private: int _Width, _Height; // Width and Height float* myVector; //Aux function for testing bool Test_Sizes(const int Width, const int Heigth); }; #endif /* LINEARMATRIX_HPP_ */ //============================================================================ // Name : linearMatrix.cpp // Author : Flores, Facundo Gabriel // Version : 0.1 // Description : This file contains the linearMatrix implementation class. // A linear matrix is a vector that represents a matrix. // We will read this kind of classes from files, because // they are generally large. But linearMatrix can represent // a 1D vector if Height is 1. //============================================================================ #include &lt;iostream&gt; using std::cout; using std::endl; using std::cerr; using std::bad_alloc; #include &lt;cstdio&gt; #include &lt;cstdlib&gt; #include &lt;ctime&gt; #include &lt;new&gt; #include "linearMatrix.hpp" #define FALSE 0 #define TRUE 1 //Test if W and H are correct bool linearMatrix::Test_Sizes(const int W, const int H) { if(W &lt; 1 || W &gt; 32500) return FALSE; if(H &lt; 1 || H&gt; 32500) return FALSE; return TRUE; } // We set the Width and Height parameters linearMatrix::linearMatrix(const int Width, const int Height) { if(Test_Sizes(Width, Height)) { _Width = Width; _Height = Height; try{ myVector = new float[_Width * _Height]; } catch(bad_alloc &amp;ex) { cerr &lt;&lt; "Exception:" &lt;&lt; ex.what(); exit(1); } } else { cout&lt;&lt;"Bad sizes!"&lt;&lt;endl; exit(1); } } linearMatrix::~linearMatrix() { delete [] myVector; } //We set a random vector using its Width and Height void linearMatrix::Generate_Random_Matrix(void) { srand(time(NULL)); for(int i = 0; i &lt; _Width; i++) for(int j = 0; j &lt; _Height; j++) { // We are putting a number between 0 and 99 myVector[i * _Width + _Height] = rand() % 100; } } //We set a diagonal dominant matrix void linearMatrix::Generate_Diagonal_Dominant(void) { for(int i = 0; i &lt; _Width; i++) for(int j = 0; j &lt; _Height; j++) { if(i == j) //Diagonal item myVector[i * _Width + j] = 32500; else myVector[i * _Width + j] = 0.5; } } //We copy V into myVector void linearMatrix::Copy_Vector(const float *V, const int Width, const int Heigth) { if(Width != _Width || Heigth != _Height) { cout&lt;&lt;"Different sizes, we cannot copy vector V"&lt;&lt;endl; exit(1); } else { for(int i = 0; i &lt; _Width; i++) for(int j = 0; j &lt; _Height; j++) { myVector[i * _Width + j] = V[i * Width + j]; } } } //We show a little matrix. Assume H &lt; 11 and W &lt; 11 void linearMatrix::Show_Little_Matrix(void) { cout.precision(5); if(_Height &lt; 11 &amp;&amp; _Width &lt; 11) { for(int i = 0; i &lt; _Width; i++) { for(int j = 0; j &lt; _Height; j++) { cout&lt;&lt;myVector[i * _Width + j]&lt;&lt;" "; } cout &lt;&lt; endl; } } else { cout &lt;&lt; "I can show only little matrices in the console " &lt;&lt; endl; } } void linearMatrix::Write_File_Matrix(const char *Path) { FILE *pFile = fopen(Path, "wb"); fwrite(&amp;_Height, sizeof(int), 1, pFile); fwrite(&amp;_Width, sizeof(int), 1, pFile); fwrite(myVector, sizeof(float), _Height * _Width, pFile); fclose(pFile); } void linearMatrix::Read_File_Matrix(const char *Path) { FILE *pFile = fopen(Path, "rb"); if(pFile == NULL){ cout &lt;&lt; "Cannot read :" &lt;&lt; Path &lt;&lt; endl; exit(1); } fread(&amp;_Height, sizeof(int), 1, pFile); fread(&amp;_Width, sizeof(int), 1, pFile); try{ myVector = new float[_Width * _Height]; } catch(bad_alloc &amp;ex) { cout &lt;&lt; "Exception:" &lt;&lt; ex.what(); exit(1); } fread(myVector, sizeof(double), _Height * _Width, pFile); } </code></pre> <p>And I'm trying to use this class with the following <code>main.cpp</code>:</p> <pre><code>//============================================================================ // Name : main.cpp // Author : Flores, Facundo Gabriel // Version : 0.1 // Description : This file is a test. //=========================================================================== #include &lt;iostream&gt; #include "linearMatrix.hpp" int main(void) { linearMatrix Matrix2(3,1); Matrix2.Generate_Diagonal_Dominant(); Matrix2.Show_Little_Matrix(); return 0; } </code></pre> <p>So the error is:</p> <blockquote> <pre><code>*** glibc detected *** /.../linearMatrix/Debug/linearMatrix: free(): invalid next size (fast): 0x00000000007f1010 *** </code></pre> </blockquote> <p>I don't know how to use <code>valgrind</code> yet. But why is the error there? The program shows me the correct output, but when the destructor is "executed" the error appears while freeing <code>myVector</code>. How to solve it?</p>
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    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USFacundoGFlores
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      1. LTLinked
    2. PL
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      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
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    1. VO
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      1. POError while freeing memory
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      1. VTUpMod
    1. COIdentifiers starting with an underscore, followed by a capital letter, such as your `_Width`, are [reserved](http://stackoverflow.com/questions/228783/what-are-the-rules-about-using-an-underscore-in-a-c-identifier) in any scope. I would keep that in mind. You are also not giving any attention to the [Rule of Three](http://stackoverflow.com/questions/4172722/what-is-the-rule-of-three) (Five), which should really be the [Rule of Zero](http://rmartinho.github.com/2012/08/15/rule-of-zero.html) in this day and age.
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      1. POError while freeing memory
      1. USchris
    2. COyou should learn how to use valgrind and debugger as fast as possible. With valgrind basic command is: "valgrind --tool=memcheck --leak-check=yes --show-reachable=yes --num-callers=20 --track-fds=yes ./test" remember about debugger flag in your compiler, in g++ it is "-g".
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      1. POError while freeing memory
      1. USCyberGuy
    3. CO@chris. Identifiers starting with an underscore are members of the class linearMatrix. I will read about Rule of Three and Rule of Zero, I have never listened about them, thank you.
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      1. POError while freeing memory
      1. USFacundoGFlores
 

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