range-expr.md

Range expressions

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

RangeExpr :
   Expression .. Expression

RangeFromExpr :
   Expression ..

RangeToExpr :
   .. Expression

RangeFullExpr :
   ..

RangeInclusiveExpr :
   Expression ..= Expression

RangeToInclusiveExpr :
   ..= 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:

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.

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

assert_eq!(x, y);

Ranges can be used in for loops:

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