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Range expressions

Syntax
RangeExpression :
RangeExpr
| RangeFromExpr
| RangeToExpr
| RangeFullExpr
| RangeInclusiveExpr
| RangeToInclusiveExpr

RangeExpr :
Expression .. Expression

RangeFromExpr :
Expression ..

RangeToExpr :
.. Expression

RangeFullExpr :
..

RangeExpr :
Expression ..= Expression

RangeToExpr :
..= Expression

The .. and ..= operators will construct an object of one of the std::ops::Range (or core::ops::Range) variants, according to the following table:

Production Syntax Type Range
RangeExpr start..end std::ops::Range start ≤ x < end
RangeFromExpr start.. std::ops::RangeFrom start ≤ x
RangeToExpr ..end std::ops::RangeTo x < end
RangeFullExpr .. std::ops::RangeFull -
RangeInclusiveExpr start..=end std::ops::RangeInclusive start ≤ x ≤ end
RangeToInclusiveExpr ..=end std::ops::RangeToInclusive x ≤ end

Examples:

# #![allow(unused_variables)]
#fn main() {
1..2;   // std::ops::Range
3..;    // std::ops::RangeFrom
..4;    // std::ops::RangeTo
..;     // std::ops::RangeFull
5..=6;  // std::ops::RangeInclusive
..=7;   // std::ops::RangeToInclusive
#}

The following expressions are equivalent.

# #![allow(unused_variables)]
#fn main() {
let x = std::ops::Range {start: 0, end: 10};
let y = 0..10;

assert_eq!(x, y);
#}

Ranges can be used in for loops:

# #![allow(unused_variables)]
#fn main() {
for i in 1..11 {
    println!("{}", i);
}
#}

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/reference/expressions/range-expr.html