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| [632] | 58 | <div class="navpath"><a class="el" href="dev_guide.html">BDM Use - in C++</a> |
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| 61 | <div class="contents"> |
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| [651] | 62 | <h1><a class="anchor" name="itfile">Writing and reading data from files </a></h1>Here we will use the <code>it_file</code> class to store some data. The program <code>write_it_file.cpp</code> looks as follows:<p> |
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| [354] | 63 | <div class="fragment"><pre class="fragment"><span class="preprocessor">#include <itpp/itcomm.h></span> |
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| [261] | 64 | |
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| 65 | <span class="keyword">using namespace </span>itpp; |
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| 66 | |
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| [538] | 67 | <span class="keywordtype">int</span> main() { |
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| 68 | <span class="comment">// Declare the it_file class</span> |
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| 69 | it_file ff; |
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| [261] | 70 | |
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| [651] | 71 | <span class="comment">// Open a file with the name "it_file_test.it"</span> |
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| 72 | ff.open ( <span class="stringliteral">"it_file_test.it"</span> ); |
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| [261] | 73 | |
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| [538] | 74 | <span class="comment">// Create some data to put into the file</span> |
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| 75 | vec a = linspace ( 1, 20, 20 ); |
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| [261] | 76 | |
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| [651] | 77 | <span class="comment">// Put the variable a into the file. The Name("a") tells the file class</span> |
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| 78 | <span class="comment">// that the next variable shall be named "a".</span> |
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| 79 | ff << Name ( <span class="stringliteral">"a"</span> ) << a; |
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| [261] | 80 | |
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| [538] | 81 | <span class="comment">// Force the file to be written to disc. This is useful when performing</span> |
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| 82 | <span class="comment">// iterations and ensures that the information is not stored in any cache</span> |
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| 83 | <span class="comment">// memory. In this simple example it is not necessary to flush the file.</span> |
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| 84 | ff.flush(); |
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| [261] | 85 | |
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| [538] | 86 | <span class="comment">// Close the file</span> |
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| 87 | ff.close(); |
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| [261] | 88 | |
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| [538] | 89 | <span class="comment">// Exit program</span> |
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| 90 | <span class="keywordflow">return</span> 0; |
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| [261] | 91 | } |
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| [651] | 92 | </pre></div><p> |
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| 93 | When you run this program you will obtain a file called <code>it_file_test.it</code> in your current directory. You can read the file into Matlab/Octave to view the data by using the following commands:<p> |
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| 94 | <div class="fragment"><pre class="fragment">itload(<span class="stringliteral">'it_file_test.it'</span>) |
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| [261] | 95 | figure(1); clf; |
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| 96 | plot(a) |
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| [651] | 97 | </pre></div><p> |
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| 98 | Note: Make sure that <code>$PREFIX/share/itpp</code> is in your Matlab/Octave path and that you run the code above from the directory where <code>it_file_test.it</code> is located (<code>$PREFIX</code> is the IT++ installation prefix; <code>/usr/local</code> by default).<p> |
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| 99 | The IT++ program <code>read_it_file.cpp</code> that reads the file and prints its content can look like this:<p> |
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| 100 | <div class="fragment"><pre class="fragment"></pre></div><p> |
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| 101 | Here is the output of the program:<p> |
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| [261] | 102 | <div class="fragment"><pre class="fragment"> |
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| 103 | a = [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20] |
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| 104 | </pre></div> </div> |
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| [651] | 105 | <hr size="1"><address style="text-align: right;"><small>Generated on Wed Oct 7 17:34:44 2009 for mixpp by |
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| [651] | 107 | <img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.9 </small></address> |
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