projects / rustc.git / blame
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1 | # Range expressions |
| 2 | ||
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3 | > **<sup>Syntax</sup>**\ |
| 4 | > _RangeExpression_ :\ | |
| 5 | > _RangeExpr_\ | |
| 6 | > | _RangeFromExpr_\ | |
| 7 | > | _RangeToExpr_\ | |
| 8 | > | _RangeFullExpr_\ | |
| 9 | > | _RangeInclusiveExpr_\ | |
| 10 | > | _RangeToInclusiveExpr_ | |
| 0531ce1d | 11 | > |
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12 | > _RangeExpr_ :\ |
| 13 | > [_Expression_] `..` [_Expression_] | |
| 14 | > | |
| 15 | > _RangeFromExpr_ :\ | |
| 16 | > [_Expression_] `..` | |
| 17 | > | |
| 18 | > _RangeToExpr_ :\ | |
| 19 | > `..` [_Expression_] | |
| 20 | > | |
| 21 | > _RangeFullExpr_ :\ | |
| 22 | > `..` | |
| 23 | > | |
| 0bf4aa26 | 24 | > _RangeInclusiveExpr_ :\ |
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25 | > [_Expression_] `..=` [_Expression_] |
| 26 | > | |
| 0bf4aa26 | 27 | > _RangeToInclusiveExpr_ :\ |
| 8faf50e0 | 28 | > `..=` [_Expression_] |
| abe05a73 | 29 | |
| 6a06907d | 30 | The `..` and `..=` operators will construct an object of one of the `std::ops::Range` (or `core::ops::Range`) variants, according to the following table: |
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31 | |
| 32 | | Production | Syntax | Type | Range | | |
| 33 | |------------------------|---------------|------------------------------|-----------------------| | |
| 34 | | _RangeExpr_ | start`..`end | [std::ops::Range] | start ≤ x < end | | |
| 35 | | _RangeFromExpr_ | start`..` | [std::ops::RangeFrom] | start ≤ x | | |
| 36 | | _RangeToExpr_ | `..`end | [std::ops::RangeTo] | x < end | | |
| 37 | | _RangeFullExpr_ | `..` | [std::ops::RangeFull] | - | | |
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38 | | _RangeInclusiveExpr_ | start`..=`end | [std::ops::RangeInclusive] | start ≤ x ≤ end | |
| 39 | | _RangeToInclusiveExpr_ | `..=`end | [std::ops::RangeToInclusive] | x ≤ end | | |
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40 | |
| 41 | Examples: | |
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42 | |
| 43 | ```rust | |
| 44 | 1..2; // std::ops::Range | |
| 45 | 3..; // std::ops::RangeFrom | |
| 46 | ..4; // std::ops::RangeTo | |
| 47 | ..; // std::ops::RangeFull | |
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48 | 5..=6; // std::ops::RangeInclusive |
| 49 | ..=7; // std::ops::RangeToInclusive | |
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50 | ``` |
| 51 | ||
| 52 | The following expressions are equivalent. | |
| 53 | ||
| 54 | ```rust | |
| 55 | let x = std::ops::Range {start: 0, end: 10}; | |
| 56 | let y = 0..10; | |
| 57 | ||
| 58 | assert_eq!(x, y); | |
| 59 | ``` | |
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60 | |
| 61 | Ranges can be used in `for` loops: | |
| 62 | ||
| 63 | ```rust | |
| 64 | for i in 1..11 { | |
| 65 | println!("{}", i); | |
| 66 | } | |
| 67 | ``` | |
| 68 | ||
| 416331ca | 69 | [_Expression_]: ../expressions.md |
| abe05a73 | 70 | |
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71 | [std::ops::Range]: https://doc.rust-lang.org/std/ops/struct.Range.html |
| 72 | [std::ops::RangeFrom]: https://doc.rust-lang.org/std/ops/struct.RangeFrom.html | |
| 73 | [std::ops::RangeTo]: https://doc.rust-lang.org/std/ops/struct.RangeTo.html | |
| 74 | [std::ops::RangeFull]: https://doc.rust-lang.org/std/ops/struct.RangeFull.html | |
| 75 | [std::ops::RangeInclusive]: https://doc.rust-lang.org/std/ops/struct.RangeInclusive.html | |
| 0531ce1d | 76 | [std::ops::RangeToInclusive]: https://doc.rust-lang.org/std/ops/struct.RangeToInclusive.html |