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    <p>Your <code>operator+</code> receives copy of the argument passed to it.</p> <pre><code> CRectangle CRectangle::operator+ (CRectangle param) { CRectangle temp; temp.width = new int; temp.height = new int; *temp.width = *width + *param.width; *temp.height = *height + *param.height; return (temp); } </code></pre> <p>In the code:</p> <pre><code>CRectangle a(3,4),b(5,6),c; c=a+b; </code></pre> <p>More specifically, in the <code>a + b</code> copy of <code>b</code> is passed to <code>a.operator+</code>. At the end of the function this copy is destroyed. </p> <p>So, to sum up:</p> <ul> <li><p>Your statement <code>c = a + b;</code> can be separated in two parts:</p> <pre><code>temp = a + b; c = temp; </code></pre></li> <li><p>The first statement is basically this:</p> <pre><code>temp = a.operator+(b); </code></pre></li> </ul> <p>Now, your <code>operator+</code> is receiving <code>param</code> by value. This means that copy of object <code>b</code> will be created and you will have two identical objects: <code>b</code> and <code>param</code>. When this function returns, <code>param</code> object will be destroyed.</p> <p>Now, everything would be good <strong>except</strong>:</p> <ul> <li><p>Even <code>b</code> and <code>param</code> are separated objects, their pointers <code>width</code> and <code>height</code> points to a single memory location. Destructor of <code>param</code> will free this memory and <code>b</code>'s pointers will point to deallocated memory locations. In order to prevent this, you need to write copy-constructor:</p> <pre><code>CRectangle::CRectangle(const CRectangle&amp; param) { width = new int; // alocate separate memory locations! height = new int; *width = *param.width; *height = *param.height; } </code></pre></li> </ul> <p>To avoid copy-on-passing, pass by const-reference instead:</p> <pre><code>CRectangle CRectangle::operator+ (const CRectangle &amp;param) </code></pre> <p>As you noted, the same thing happens with <code>operator=</code>.</p> <p>Also, this code:</p> <pre><code>temp.width = new int; temp.height = new int; *temp.width = *width + *param.width; *temp.height = *height + *param.height; </code></pre> <p>can be rewritten as (also the types of <code>width</code> and <code>height</code> should be changed to <code>int</code>):</p> <pre><code>temp.width = width + param.width temp.height = height + param.height; </code></pre> <p>There's no need to have pointers as fields in your class, if they serve just like regular values.</p>
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    1. USNemanja Boric
    1. USNemanja Boric
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    1. CObut it would receive the copy of temp right. why b is deleted?
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      1. USAkshat Aggarwal
    2. CO@AkshatAggarwal `b` is not deleted Copy of the `b` is deleted - see my edit for more explanation.
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      1. USNemanja Boric
    3. COsee i have an area function which multiplies width and height. So, if i call it on b before c=a+b, it gives 30, but after it gives a random value. If the copy is deleted, why is that happening? See the edit
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