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POWriting array to file code does not work (C++)
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  1. POWriting array to file code does not work (C++)
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    copied!<p><strong>UPDATE: If anyone is reading this and having a similar problem, it seems that the problem was where I converted a double to an int. Where I thought for example 54 was stored as 54.000..., it was actually stored as 53.99999... and when changing to int, it became 53. A workaround to this problem which I found out is to simply add 0.5 and so the code that was</strong></p> <pre><code>int output_buffer=O[m][n]; </code></pre> <p><strong>becomes</strong></p> <pre><code>int output_buffer=O[m][n]+0.5; </code></pre> <hr> <p>I have a two dimensional array of doubles called "O". Where </p> <pre><code>double O[3][3]; </code></pre> <p>I use these two functions right after the other in this exact order;</p> <pre><code>... displaymatrixO(); writedecrypted(); ... </code></pre> <p>Where </p> <pre><code>int displaymatrixO() { cout &lt;&lt; "O is:" &lt;&lt; "\n"; for (int n=0;n&lt;3;n++) for (int m=0;m&lt;3;m++) { cout &lt;&lt; O[m][n]; if (m == 2) cout &lt;&lt; "\n"; else cout &lt;&lt; " "; } } </code></pre> <p>And </p> <pre><code>int writedecrypted() { for (int n=0;n&lt;3;n++) for (int m=0;m&lt;3;m++) { int output_buffer=O[m][n]; fputc (output_buffer,opFile); } } </code></pre> <p>Where</p> <pre><code>FILE *opFile; opFile=fopen ("decrypted.txt","wb"); ... </code></pre> <p>When the program is run, the first function (displaymatrixO) outputs the matrix O to screen in this fashion:</p> <pre><code>O is: 49 50 51 52 53 54 3 3 3 </code></pre> <p>Which is correct, this is what O is supposed to be. </p> <p>The second function then is supposed to typecast and write the individual values of the matrix to a file where each value takes up the space of 8 bits/ 1 byte. When I use a hex editor and look at the file, this is what the file looks like(in hex):</p> <pre><code>0x31 0x32 0x33 0x33 0x35 0x35 0x03 0x03 0x03 </code></pre> <p>In 8-bit signed integer format (i.e. how O is displayed using displaymatrixO), this is what it looks like:</p> <pre><code>49 50 51 51 53 53 3 3 3 </code></pre> <p>i.e. </p> <pre><code>49 50 51 51 53 53 3 3 3 </code></pre> <p>It seems to copy O[2][0] onto O[0][1] and O[1][1] onto O[2][1]. I have looked at the code again and again and I can't seem to figure out where I am going wrong! Help if you can...</p>
 

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