From da73d25416a8d3f6be56b62f513af1868a583e67 Mon Sep 17 00:00:00 2001 From: kemchenj Date: Fri, 22 Sep 2017 20:21:07 +0800 Subject: [PATCH] =?UTF-8?q?12=EF=BC=8CSubscripts=EF=BC=8Cfor=20Swift=204.0?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- source/chapter2/12_Subscripts.md | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/source/chapter2/12_Subscripts.md b/source/chapter2/12_Subscripts.md index 56e35e45..80532797 100755 --- a/source/chapter2/12_Subscripts.md +++ b/source/chapter2/12_Subscripts.md @@ -14,6 +14,9 @@ > 2.2 > 校对：[SketchK](https://github.com/SketchK) 2016-05-13 > 3.0.1，shanks，2016-11-13 + +> 4.0 +> 校对：[kemchenj](https://kemchenj.github.io/) 2017-09-21 本页包含内容： @@ -111,16 +114,16 @@ struct Matrix { self.columns = columns grid = Array(count: rows * columns, repeatedValue: 0.0) } - func indexIsValidForRow(row: Int, column: Int) -> Bool { + func indexIsValid(row: Int, column: Int) -> Bool { return row >= 0 && row < rows && column >= 0 && column < columns } subscript(row: Int, column: Int) -> Double { get { - assert(indexIsValidForRow(row, column: column), "Index out of range") + assert(indexIsValid(row: row, column: column), "Index out of range") return grid[(row * columns) + column] } set { - assert(indexIsValidForRow(row, column: column), "Index out of range") + assert(indexIsValid(row: row, column: column), "Index out of range") grid[(row * columns) + column] = newValue } } @@ -150,10 +153,10 @@ matrix[1, 0] = 3.2 ![](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Art/subscriptMatrix02_2x.png) -`Matrix`下标的 getter 和 setter 中都含有断言，用来检查下标入参`row`和`column`的值是否有效。为了方便进行断言，`Matrix`包含了一个名为`indexIsValidForRow(_:column:)`的便利方法，用来检查入参`row`和`column`的值是否在矩阵范围内： +`Matrix`下标的 getter 和 setter 中都含有断言，用来检查下标入参`row`和`column`的值是否有效。为了方便进行断言，`Matrix`包含了一个名为`indexIsValid(row:column:)`的便利方法，用来检查入参`row`和`column`的值是否在矩阵范围内： ```swift -func indexIsValidForRow(row: Int, column: Int) -> Bool { +func indexIsValid(row: Int, column: Int) -> Bool { return row >= 0 && row < rows && column >= 0 && column < columns } ```