From 6361aa0a2a2419aa1e85dedaf8061d0e29ad59cc Mon Sep 17 00:00:00 2001 From: Shindo Date: Mon, 9 Jun 2014 19:11:20 +0800 Subject: [PATCH 1/4] =?UTF-8?q?=E5=8D=A0=E5=9D=91=20Control=20Flow:=20Cond?= =?UTF-8?q?itional=20Statements?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- source/chapter2/05_Control_Flow.md | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/source/chapter2/05_Control_Flow.md b/source/chapter2/05_Control_Flow.md index efb13e9c..ba2fbb9f 100644 --- a/source/chapter2/05_Control_Flow.md +++ b/source/chapter2/05_Control_Flow.md @@ -262,12 +262,14 @@ println("Game over!") 循环条件（`while square < finalSquare`）和 `while` 方式相同，但是只会在循环结束后进行计算。在这个游戏中，`do-while` 表现得比 `while` 循环更好。 `do-while` 方式会在条件判断 `square` 没有超出后直接运行 `square += board[square]` ，这种方式可以去掉 `while` 版本中的数组越界判断。 + ## 条件语句 根据特定的条件执行特定的代码通常是十分有用的，例如：当错误发生时，你可能想运行额外的代码；或者，当输入的值太大或太小时，向用户显示一条消息等。要实现这些功能，你就需要使用*条件语句*。 Swift 提供两种类型的条件语句：`if`语句和`switch`语句。通常，当条件较为简单且可能的情况很少时，使用`if`语句。而`switch`语句更适用于复杂的条件、可能的情况很多且需要用到模式匹配(pattern-matching)的情境。 + ### If `if`语句最简单的形式就是只包含一个条件，当且仅当该条件为`真`时，才执行相关代码： @@ -325,6 +327,7 @@ if temperatureInFahrenheit <= 32 { 在这个例子中，由于既不冷也不热，所以不会触发`if`或`else if`分支，也就不会打印任何消息。 + ### Switch `switch`语句会尝试把某个值与若干个模式(pattern)进行匹配。根据第一个匹配成功的模式，`switch`语句会执行对应的代码。当有可能的情况较多时，通常用`switch`语句替换`if`语句。 @@ -512,8 +515,8 @@ case let (x, y): -在上面的例子中，`switch`语句会判断某个点是否在绿色的对角线`x == y`上，是否在紫色的对角线'x == -y'上，或者不在对角线上。 +在上面的例子中，`switch`语句会判断某个点是否在绿色的对角线`x == y`上，是否在紫色的对角线`x == -y`上，或者不在对角线上。 这三个*case*都声明了常量`x`和`y`的占位符，用于临时获取元组`yetAnotherPoint`的两个值。这些常量被用作`where`语句的一部分，从而创建一个动态的过滤器(filter)。当且仅当`where`语句的条件为`真`时，匹配到的*case*块才会被执行。 -就像是值绑定中的例子，由于最后一个*case*块匹配了余下所有可能的值，`switch`语句就已经完备了，因此不需要再书写默认块。 +就像是值绑定中的例子，由于最后一个*case*块匹配了余下所有可能的值，`switch`语句就已经完备了，因此不需要再书写默认块。 \ No newline at end of file From cbb71a1267e4dc1bca138f314af848ee90c90608 Mon Sep 17 00:00:00 2001 From: Shindo Date: Tue, 10 Jun 2014 13:06:26 +0800 Subject: [PATCH 2/4] =?UTF-8?q?=E4=BF=AE=E6=AD=A3=E4=B8=80=E4=BA=9B?= =?UTF-8?q?=E7=96=8F=E5=BF=BD?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- source/chapter3/10_Statements.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/source/chapter3/10_Statements.md b/source/chapter3/10_Statements.md index 3206fbf7..3f603590 100644 --- a/source/chapter3/10_Statements.md +++ b/source/chapter3/10_Statements.md @@ -67,7 +67,7 @@ for `initialzation`; `condition`; `increment` { > *for-statement* → **for** [*for-init*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Statements.html#//apple_ref/swift/grammar/for-init) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* [*code-block*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/swift/grammar/code-block) -> *for-statement* → **for ( ** [*for-init*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Statements.html#//apple_ref/swift/grammar/for-init) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **)** [*code-block*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/swift/grammar/code-block) +> *for-statement* → **for (** [*for-init*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Statements.html#//apple_ref/swift/grammar/for-init) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **)** [*code-block*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/swift/grammar/code-block) > *for-statement* → [*variable-declaration*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/swift/grammar/variable-declaration) | [*expression-list*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression-list) @@ -366,7 +366,7 @@ continue `label name` ```swift return -return `表达式` +return `expression` ``` 当`return`语句后面带表达式时，表达式的值将会返回给调用者。如果表达式值的类型与调用者期望的类型不匹配，Swift 则会在返回表达式的值之前将表达式值的类型转换为调用者期望的类型。 From 5dda87e7fdee7327050ba7640131baa8e2a74409 Mon Sep 17 00:00:00 2001 From: Shindo Date: Tue, 10 Jun 2014 13:06:26 +0800 Subject: [PATCH 3/4] =?UTF-8?q?=E4=BF=AE=E6=AD=A3=E4=B8=80=E4=BA=9B?= =?UTF-8?q?=E7=96=8F=E5=BF=BD?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- source/chapter3/10_Statements.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/source/chapter3/10_Statements.md b/source/chapter3/10_Statements.md index 3206fbf7..3f603590 100644 --- a/source/chapter3/10_Statements.md +++ b/source/chapter3/10_Statements.md @@ -67,7 +67,7 @@ for `initialzation`; `condition`; `increment` { > *for-statement* → **for** [*for-init*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Statements.html#//apple_ref/swift/grammar/for-init) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* [*code-block*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/swift/grammar/code-block) -> *for-statement* → **for ( ** [*for-init*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Statements.html#//apple_ref/swift/grammar/for-init) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **)** [*code-block*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/swift/grammar/code-block) +> *for-statement* → **for (** [*for-init*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Statements.html#//apple_ref/swift/grammar/for-init) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **;** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* **)** [*code-block*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/swift/grammar/code-block) > *for-statement* → [*variable-declaration*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/swift/grammar/variable-declaration) | [*expression-list*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression-list) @@ -366,7 +366,7 @@ continue `label name` ```swift return -return `表达式` +return `expression` ``` 当`return`语句后面带表达式时，表达式的值将会返回给调用者。如果表达式值的类型与调用者期望的类型不匹配，Swift 则会在返回表达式的值之前将表达式值的类型转换为调用者期望的类型。 From 3cf85e3070af3ff0c9a1d22b369034ab6e64f491 Mon Sep 17 00:00:00 2001 From: Shindo Date: Tue, 10 Jun 2014 13:15:08 +0800 Subject: [PATCH 4/4] no message --- source/chapter3/10_Statements.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/source/chapter3/10_Statements.md b/source/chapter3/10_Statements.md index 3f603590..c7543e99 100644 --- a/source/chapter3/10_Statements.md +++ b/source/chapter3/10_Statements.md @@ -375,4 +375,4 @@ return `expression` > GRAMMAR OF A RETURN STATEMENT -> *return-statement* → **return** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* +> *return-statement* → **return** [*expression*](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) *opt* \ No newline at end of file