63 lines
1.3 KiB
Markdown
63 lines
1.3 KiB
Markdown
While Loop
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==========
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{{#include ../links.md}}
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`while` loops follow C syntax.
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Like C, `continue` can be used to skip to the next iteration, by-passing all following statements;
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`break` can be used to break out of the loop unconditionally.
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~~~admonish tip.small "Tip: Disable `while` loops"
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`while` loops can be disabled via [`Engine::set_allow_looping`][options].
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~~~
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```rust
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let x = 10;
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while x > 0 {
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x -= 1;
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if x < 6 { continue; } // skip to the next iteration
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print(x);
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if x == 5 { break; } // break out of while loop
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}
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```
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While Expression
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----------------
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Like Rust, `while` statements can also be used as _expressions_.
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The `break` statement takes an optional expression that provides the return value.
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The default return value of a `while` expression is [`()`].
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~~~admonish tip.small "Tip: Disable all loop expressions"
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Loop expressions can be disabled via [`Engine::set_allow_loop_expressions`][options].
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~~~
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```js
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let x = 0;
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// 'while' can be used just like an expression
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let result = while x < 100 {
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if is_magic_number(x) {
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// if the 'while' loop breaks here, return a specific value
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break get_magic_result(x);
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}
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x += 1;
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// ... if the 'while' loop exits here, the return value is ()
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};
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if result == () {
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print("Magic number not found!");
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} else {
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print(`Magic result = ${result}!`);
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}
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```
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