108 lines
3 KiB
Markdown
108 lines
3 KiB
Markdown
# Hello, Python
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{:.no_toc}
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<nav markdown="1" class="toc-class">
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* TOC
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{:toc}
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</nav>
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## The goal
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This is the first step in running something in Python.
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Questions to [David Rotermund](mailto:davrot@uni-bremen.de)
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## These are the same stings
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```python
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some_string = "this is a string"
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some_string = 'this is a string'
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```
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```python
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print(some_string)
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```
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Output:
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```python
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this is a string
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```
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## These are comments
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```python
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# This is comment
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a = 1 # This is a comment too! (not the a=1)
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```
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## [print](https://docs.python.org/3/library/functions.html#print)
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```python
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print(*objects, sep=' ', end='\n', file=None, flush=False)
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```
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> Print objects to the text stream file, separated by sep and followed by end. sep, end, file, and flush, if present, must be given as keyword arguments.
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>
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> All non-keyword arguments are converted to strings like str() does and written to the stream, separated by sep and followed by end. Both sep and end must be strings; they can also be None, which means to use the default values. If no objects are given, print() will just write end.
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>
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> The file argument must be an object with a write(string) method; if it is not present or None, sys.stdout will be used. Since printed arguments are converted to text strings, print() cannot be used with binary mode file objects. For these, use file.write(...) instead.
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>
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> Output buffering is usually determined by file. However, if flush is true, the stream is forcibly flushed.
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## [Help!](https://docs.python.org/3/library/functions.html#help)
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### Help for a function
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Here the function round() as an example. Please note that () is missing with the help function:
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```python
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help(round)
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```
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```python
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Help on built-in function round in module builtins:
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round(number, ndigits=None)
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Round a number to a given precision in decimal digits.
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The return value is an integer if ndigits is omitted or None. Otherwise
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the return value has the same type as the number. ndigits may be negative.
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```
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### Help for a keyword
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Keywords are build-in core instructions.
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```python
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help("for")
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```
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```python
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The "for" statement
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*******************
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The "for" statement is used to iterate over the elements of a sequence
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(such as a string, tuple or list) or other iterable object:
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for_stmt ::= "for" target_list "in" expression_list ":" suite
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["else" ":" suite]
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The expression list is evaluated once; it should yield an iterable
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object. An iterator is created for the result of the
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[...]
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```
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In the case when you are not sure if something is a keyword, you can check it like [this](https://docs.python.org/3/library/keyword.html):
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```python
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import keyword
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print(keyword.kwlist)
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print(keyword.softkwlist)
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```
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```python
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['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'nonlocal', 'not', 'or', 'pass', 'raise', 'return', 'try', 'while', 'with', 'yield']
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['_', 'case', 'match']
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```
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