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python-cheatsheet
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Bytes and Memoryview

pull/54/head
Jure Šorn 4 years ago
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5a6266716a
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37c83f049e
2 changed files with 18 additions and 14 deletions
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  1. 15
      README.md
  2. 17
      index.html

15
README.md
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@ -1912,16 +1912,16 @@ Bytes
```python
<bytes> = bytes(<coll_of_ints>) # Ints must be in range from 0 to 255.
<bytes> = bytes(<str>, 'utf-8') # Or: <str>.encode('utf-8')
<bytes> = <int>.to_bytes(n_bytes, byteorder='big/little', signed=False)
<bytes> = bytes.fromhex('<hex>')
<bytes> = <int>.to_bytes(n_bytes) # Also: `byteorder='big/little', signed=False`.
<bytes> = bytes.fromhex('<hex>') # Hex numbers can be separated by spaces.
```
### Decode
```python
<list> = list(<bytes>) # Returns ints in range from 0 to 255.
<str> = str(<bytes>, 'utf-8') # Or: <bytes>.decode('utf-8')
<int> = int.from_bytes(<bytes>, byteorder='big/little', signed=False)
'<hex>' = <bytes>.hex()
<int> = int.from_bytes(<bytes>) # Also: `byteorder='big/little', signed=False`.
'<hex>' = <bytes>.hex() # Returns a string of hexadecimal numbers.
```
### Read Bytes from File
@ -2011,10 +2011,13 @@ Memory View
<bytes> = bytes(<mview>) # Creates a new bytes object.
<bytes> = <bytes>.join(<coll_of_mviews>) # Joins mviews using bytes object as sep.
<array> = array('<typecode>', <mview>) # Treats mview as a sequence of numbers.
```
```python
<list> = list(<mview>) # Returns list of ints or floats.
<str> = str(<mview>, 'utf-8') # Treats mview as a bytes object.
<int> = int.from_bytes(<mview>, byteorder='big/little', signed=False)
'<hex>' = <mview>.hex()
<int> = int.from_bytes(<mview>, …) # `byteorder='big/little', signed=False`.
'<hex>' = <mview>.hex() # Treats mview as a bytes object.
```

17
index.html
View File

@ -1701,14 +1701,14 @@ db = connector.connect(host=&lt;str&gt;, user=&lt;str&gt;, password=&lt;str&gt;,
<div><h3 id="encode-1">Encode</h3><pre><code class="python language-python hljs">&lt;bytes&gt; = bytes(&lt;coll_of_ints&gt;) <span class="hljs-comment"># Ints must be in range from 0 to 255.</span>
&lt;bytes&gt; = bytes(&lt;str&gt;, <span class="hljs-string">'utf-8'</span>) <span class="hljs-comment"># Or: &lt;str&gt;.encode('utf-8')</span>
&lt;bytes&gt; = &lt;int&gt;.to_bytes(n_bytes, byteorder=<span class="hljs-string">'big/little'</span>, signed=<span class="hljs-keyword">False</span>)
&lt;bytes&gt; = bytes.fromhex(<span class="hljs-string">'&lt;hex&gt;'</span>)
&lt;bytes&gt; = &lt;int&gt;.to_bytes(n_bytes) <span class="hljs-comment"># Also: `byteorder='big/little', signed=False`.</span>
&lt;bytes&gt; = bytes.fromhex(<span class="hljs-string">'&lt;hex&gt;'</span>) <span class="hljs-comment"># Hex numbers can be separated by spaces.</span>
</code></pre></div>
<div><h3 id="decode-1">Decode</h3><pre><code class="python language-python hljs">&lt;list&gt; = list(&lt;bytes&gt;) <span class="hljs-comment"># Returns ints in range from 0 to 255.</span>
&lt;str&gt; = str(&lt;bytes&gt;, <span class="hljs-string">'utf-8'</span>) <span class="hljs-comment"># Or: &lt;bytes&gt;.decode('utf-8')</span>
&lt;int&gt; = int.from_bytes(&lt;bytes&gt;, byteorder=<span class="hljs-string">'big/little'</span>, signed=<span class="hljs-keyword">False</span>)
<span class="hljs-string">'&lt;hex&gt;'</span> = &lt;bytes&gt;.hex()
&lt;int&gt; = int.from_bytes(&lt;bytes&gt;) <span class="hljs-comment"># Also: `byteorder='big/little', signed=False`.</span>
<span class="hljs-string">'&lt;hex&gt;'</span> = &lt;bytes&gt;.hex() <span class="hljs-comment"># Returns a string of hexadecimal numbers.</span>
</code></pre></div>
<div><h3 id="readbytesfromfile">Read Bytes from File</h3><pre><code class="python language-python hljs"><span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">read_bytes</span><span class="hljs-params">(filename)</span>:</span>
@ -1782,12 +1782,13 @@ db = connector.connect(host=&lt;str&gt;, user=&lt;str&gt;, password=&lt;str&gt;,
&lt;bytes&gt; = bytes(&lt;mview&gt;) <span class="hljs-comment"># Creates a new bytes object.</span>
&lt;bytes&gt; = &lt;bytes&gt;.join(&lt;coll_of_mviews&gt;) <span class="hljs-comment"># Joins mviews using bytes object as sep.</span>
&lt;array&gt; = array(<span class="hljs-string">'&lt;typecode&gt;'</span>, &lt;mview&gt;) <span class="hljs-comment"># Treats mview as a sequence of numbers.</span>
&lt;list&gt; = list(&lt;mview&gt;) <span class="hljs-comment"># Returns list of ints or floats.</span>
&lt;str&gt; = str(&lt;mview&gt;, <span class="hljs-string">'utf-8'</span>) <span class="hljs-comment"># Treats mview as a bytes object.</span>
&lt;int&gt; = int.from_bytes(&lt;mview&gt;, byteorder=<span class="hljs-string">'big/little'</span>, signed=<span class="hljs-keyword">False</span>)
<span class="hljs-string">'&lt;hex&gt;'</span> = &lt;mview&gt;.hex()
</code></pre></div>
<pre><code class="python language-python hljs">&lt;list&gt; = list(&lt;mview&gt;) <span class="hljs-comment"># Returns list of ints or floats.</span>
&lt;str&gt; = str(&lt;mview&gt;, <span class="hljs-string">'utf-8'</span>) <span class="hljs-comment"># Treats mview as a bytes object.</span>
&lt;int&gt; = int.from_bytes(&lt;mview&gt;, …) <span class="hljs-comment"># `byteorder='big/little', signed=False`.</span>
<span class="hljs-string">'&lt;hex&gt;'</span> = &lt;mview&gt;.hex() <span class="hljs-comment"># Treats mview as a bytes object.</span>
</code></pre>
<div><h2 id="deque"><a href="#deque" name="deque">#</a>Deque</h2><p><strong>A thread-safe list with efficient appends and pops from either side. Pronounced "deck".</strong></p><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> collections <span class="hljs-keyword">import</span> deque
&lt;deque&gt; = deque(&lt;collection&gt;, maxlen=<span class="hljs-keyword">None</span>)
</code></pre></div>

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