Snahal Kumar
9a6e8b1635
The video link is no longer available on youtube. It is updated with another link which I have personally reviewed and has good-quality content of 18 minutes in English has high viewers and is one of the most popular C++ channels on youtube. Also, a free e-book of lambda is provided by the content creator.
66 lines
1.9 KiB
Markdown
66 lines
1.9 KiB
Markdown
# Lambda Functions in C++
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A lambda function, or simply "lambda", is an anonymous (unnamed) function that is defined in place, within your source code, and with a concise syntax. Lambda functions were introduced in C++11 and have since become a widely used feature, especially in combination with the Standard Library algorithms.
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## Syntax
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Here is a basic syntax of a lambda function in C++:
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```cpp
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[capture-list](parameters) -> return_type {
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// function body
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};
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```
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- **capture-list**: A list of variables from the surrounding scope that the lambda function can access.
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- **parameters**: The list of input parameters, just like in a regular function. Optional.
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- **return_type**: The type of the value that the lambda function will return. This part is optional, and the compiler can deduce it in many cases.
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- **function body**: The code that defines the operation of the lambda function.
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## Usage Examples
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Here are a few examples to demonstrate the use of lambda functions in C++:
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- Lambda function with no capture, parameters, or return type.
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```cpp
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auto printHello = []() {
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std::cout << "Hello, World!" << std::endl;
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};
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printHello(); // Output: Hello, World!
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```
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- Lambda function with parameters.
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```cpp
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auto add = [](int a, int b) {
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return a + b;
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};
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int result = add(3, 4); // result = 7
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```
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- Lambda function with capture-by-value.
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```cpp
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int multiplier = 3;
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auto times = [multiplier](int a) {
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return a * multiplier;
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};
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int result = times(5); // result = 15
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```
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- Lambda function with capture-by-reference.
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```cpp
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int expiresInDays = 45;
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auto updateDays = [&expiresInDays](int newDays) {
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expiresInDays = newDays;
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};
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updateDays(30); // expiresInDays = 30
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```
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Note that, when using the capture by reference, any change made to the captured variable *inside* the lambda function will affect its value in the surrounding scope.
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- [Lambdas in C++](https://youtu.be/MH8mLFqj-n8)
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- [Lambda Expressions](https://en.cppreference.com/w/cpp/language/lambda)
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