101 lines
2 KiB
Markdown
101 lines
2 KiB
Markdown
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# Flow Control while, pass, break, continue
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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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While we wait...
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Questions to [David Rotermund](mailto:davrot@uni-bremen.de)
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**Logic blocks need to be indented. Preferable with 4 spaces!**
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## [The while statement](https://docs.python.org/3/reference/compound_stmts.html#the-while-statement)
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```python
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i = 0
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while i < 3:
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print(i)
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i += 1
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```
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Output
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```python
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0
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1
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2
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```
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## The full statement
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```python
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while_stmt ::= "while" assignment_expression ":" suite
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["else" ":" suite]
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```
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## [pass](https://docs.python.org/3/reference/simple_stmts.html#the-pass-statement)
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Since Python uses indents as definition for a functional block it needs pass for signaling an empty functional block.
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> pass is a null operation — when it is executed, nothing happens. It is useful as a placeholder when a statement is required syntactically, but no code needs to be executed
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```python
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pass_stmt ::= "pass"
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```
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## [break](https://docs.python.org/3/reference/simple_stmts.html#the-break-statement)
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> break may only occur syntactically nested in a for or while loop, but not nested in a function or class definition within that loop.
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> It terminates the nearest enclosing loop, skipping the optional else clause if the loop has one.
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> If a for loop is terminated by break, the loop control target keeps its current value.
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```python
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break_stmt ::= "break"
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```
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```python
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for i in range(0, 5):
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if i == 2:
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break
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print(i)
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```
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Output:
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```python
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0
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1
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```
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## [continue](https://docs.python.org/3/reference/simple_stmts.html#the-continue-statement)
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> continue may only occur syntactically nested in a for or while loop, but not nested in a function or class definition within that loop. It continues with the next cycle of the nearest enclosing loop.
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```python
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continue_stmt ::= "continue"
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```
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```python
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for i in range(0, 5):
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if i == 2:
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continue
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print(i)
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```
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Output:
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```python
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0
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1
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3
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4
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```
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