range-expr.md

r[expr.range]

Range expressions

r[expr.range.syntax]

RangeExpression ->
      RangeExpr
    | RangeFromExpr
    | RangeToExpr
    | RangeFullExpr
    | RangeInclusiveExpr
    | RangeToInclusiveExpr

RangeExpr -> Expression `..` Expression

RangeFromExpr -> Expression `..`

RangeToExpr -> `..` Expression

RangeFullExpr -> `..`

RangeInclusiveExpr -> Expression `..=` Expression

RangeToInclusiveExpr -> `..=` Expression

r[expr.range.behavior] 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:

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

r[expr.range.equivalence] The following expressions are equivalent.

let x = std::ops::Range {start: 0, end: 10};
let y = 0..10;

assert_eq!(x, y);

r[expr.range.for] Ranges can be used in for loops:

for i in 1..11 {
    println!("{}", i);
}