What is the exact difference between r+ and w+ modes?
<p>I tried to use both of them opening a file but got the same result. </p>

<p><code>w+</code> is supposed to create a new file if it doesn't exist while <code>r+</code> not. 
<strong>Is this the only difference?</strong></p>

<p>For example, this is an <strong>initial file <code>file.txt</code></strong></p>

<pre><code>Line 1
Line 2
Line 3
</code></pre>

<p>1) <strong><code>file.txt</code></strong> after implementing of <strong><code>r+</code> mode</strong> (writing the word "hello")</p>

<pre><code>hello
</code></pre>

<p>2) <strong><code>file.txt</code></strong> after implementing of <strong><code>w+</code></strong> <strong>mode</strong></p>

<pre><code>hello
</code></pre>

<p>I guessed that <code>r+</code> would append an input to the beginning of the file.</p>

<p>EDITED:
So, the 1st difference is about creating a file that doesn't exist and the 2nd difference is that r+ overwrites while w+ truncates, right? (than the question arises whether overwriting and truncating are the same concepts or not) </p>