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@@ -126,13 +126,9 @@ initialize it in the expression.
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In the previous section, we mentioned that the `auto` keyword cannot be used
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In the previous section, we mentioned that the `auto` keyword cannot be used
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in the parameter list because it would conflict with the functionality of the template.
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in the parameter list because it would conflict with the functionality of the template.
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But Lambda expressions are not ordinary functions, so Lambda expressions are not templated.
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But lambda expressions are not regular functions, without further specification on the typed parameter list, lambda expressions cannot utilize templates. Fortunately, this trouble
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This has caused us some trouble: the parameter table cannot be generalized,
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only exists in C++11, starting with C++14. The formal parameters of the lambda function
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and the parameter table type must be clarified.
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can use the `auto` keyword to utilize template generics:
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Fortunately, this trouble only exists in C++11, starting with C++14.
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The formal parameters of the Lambda function can use the `auto` keyword
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to generate generic meanings:
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```cpp
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```cpp
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void lambda_generic() {
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void lambda_generic() {
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@@ -221,7 +217,7 @@ int foo(int a, int b, int c) {
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;
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;
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}
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}
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int main() {
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int main() {
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// bind parameter 1, 2 on function foo,
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// bind parameter 1, 2 on function foo,
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// and use std::placeholders::_1 as placeholder for the first parameter.
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// and use std::placeholders::_1 as placeholder for the first parameter.
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auto bindFoo = std::bind(foo, std::placeholders::_1, 1,2);
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auto bindFoo = std::bind(foo, std::placeholders::_1, 1,2);
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// when call bindFoo, we only need one param left
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// when call bindFoo, we only need one param left
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@@ -483,8 +479,8 @@ int main() {
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// "str: Hello world."
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// "str: Hello world."
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std::cout << "str: " << str << std::endl;
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std::cout << "str: " << str << std::endl;
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// use push_back(const T&&),
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// use push_back(const T&&),
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// no copy the string will be moved to vector,
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// no copy the string will be moved to vector,
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// and therefore std::move can reduce copy cost
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// and therefore std::move can reduce copy cost
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v.push_back(std::move(str));
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v.push_back(std::move(str));
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// str is empty now
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// str is empty now
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@@ -107,11 +107,9 @@ void lambda_expression_capture() {
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### 泛型 Lambda
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### 泛型 Lambda
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上一节中我们提到了 `auto` 关键字不能够用在参数表里,这是因为这样的写法会与模板的功能产生冲突。
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上一节中我们提到了 `auto` 关键字不能够用在参数表里,这是因为这样的写法会与模板的功能产生冲突。
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但是 Lambda 表达式并不是普通函数,所以 Lambda 表达式并不能够模板化。
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但是 Lambda 表达式并不是普通函数,所以在没有明确指明参数表类型的情况下,Lambda 表达式并不能够模板化。
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这就为我们造成了一定程度上的麻烦:参数表不能够泛化,必须明确参数表类型。
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幸运的是,这种麻烦只存在于 C++11 中,从 C++14 开始,Lambda 函数的形式参数可以使用 `auto`
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关键字来产生意义上的泛型:
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幸运的是,这种麻烦只存在于 C++11 中,从 C++14 开始,
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Lambda 函数的形式参数可以使用 `auto` 关键字来产生意义上的泛型:
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```cpp
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```cpp
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auto add = [](auto x, auto y) {
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auto add = [](auto x, auto y) {
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