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POMatrix Arithmetic using Vectors in C++ causing segmentation faults
 

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  1. POMatrix Arithmetic using Vectors in C++ causing segmentation faults
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    <p>I'm having some issues passing vectors to functions. My concern is not with my logic itself, as if I need to adjust later I will. My program requirements state that I must have separate functions that build the matrices, print the final matrix, and ones to perform the desired mathematical operations. I'm not concerned with help on the math logic.</p> <p>It seems that I have the "hard' stuff down, for example, creating a vector of a vector, etc, but I'm having trouble passing the vectors to functions etc.</p> <pre><code>#include &lt;iostream&gt; #include &lt;iomanip&gt; #include &lt;vector&gt; using namespace std; using std::vector; void build(); void printMatrix(vector&lt;vector&lt;int&gt; &gt; ); int row=0, col=0; vector&lt;vector&lt;int&gt; &gt; matrix(row, vector&lt;int&gt; (col) ); vector&lt;vector&lt;int&gt; &gt; matrix2(row, vector&lt;int&gt; (col) ); vector&lt;vector&lt;int&gt; &gt; matrix3(row, vector&lt;int&gt; (col) ); int main(){ build(); addMatrix(); printMatrix(matrix3); return 0; } //==================================================== void build(){ //currently intended just to build 2x matrices of different increasing data int k=0, l=5; cout&lt;&lt;"Enter the number of rows for each Matrix: "&lt;&lt;endl; cin&gt;&gt;row; cout&lt;&lt;"Enter the number of columns for each Matrix: "&lt;&lt;endl; cin&gt;&gt;col; for( int i = 0; i &lt; row; i++ ) { for ( int j = 0; j &lt; col; j++ ){ matrix[i][j] = k++; matrix2[i][j] = l++; } } </code></pre> <p>I'm using Global Variables, because I want the Rows &amp; Columns to stay the same and in the program, I'm only going to be able to call one of the mathematical functions at at time.</p> <pre><code>void printMatrix(vector&lt;vector&lt;int&gt; &gt; newMatrix3){ for ( int i = 0; i &lt; row; i++ ) { for ( int j = 0; j &lt; col; j++ ) cout&lt;&lt; setw ( 3 ) &lt;&lt; newMatrix3[i][j] &lt;&lt;' '; cout&lt;&lt;'\n'; } } //========================================= void addMatrix(){ for(int i = 0; i &lt; row; i++){ for(int j = 0; j &lt; col; j++) matrix3[i][j]=(matrix[i][j]+matrix2[i][j]); } </code></pre> <p>}</p> <p>This program compiles 100% so if you see a syntax error it's because my copy + paste messed up. As soon as I enter the dimensions for the matrix, the program crashes with a segmentation fault. I'm <em>very</em> new to C++, so this is very frustrating. I'm also all ears to take suggestions on style/best practice. I have the feeling that my use of global variables is not ideal....but I'm under instructions to make the arithmetic functions as re-usable as possible. Also, I don't think I'm making the best use of functions. </p> <p>Thank you.</p>
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    1. COThat looks like homework, no ;)
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    2. COIt does to me, too... :).
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    3. COIt was homework, I just didn't know about the 'homework' tag until after I made my first post. I was having a real issue with vectors initialization, which was not part of my homework assignment though.
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