Range expressions - The Rust Reference

# 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:

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