How to implement a custom comparator in C++ STL?

The steps to implement the strategy pattern in C++ are as follows: define the strategy interface and declare the methods that need to be executed. Create specific strategy classes, implement the interface respectively and provide different algorithms. Use a context class to hold a reference to a concrete strategy class and perform operations through it.

Golang and C++ are garbage collected and manual memory management programming languages ​​respectively, with different syntax and type systems. Golang implements concurrent programming through Goroutine, and C++ implements it through threads. Golang memory management is simple, and C++ has stronger performance. In practical cases, Golang code is simpler and C++ has obvious performance advantages.

Nested exception handling is implemented in C++ through nested try-catch blocks, allowing new exceptions to be raised within the exception handler. The nested try-catch steps are as follows: 1. The outer try-catch block handles all exceptions, including those thrown by the inner exception handler. 2. The inner try-catch block handles specific types of exceptions, and if an out-of-scope exception occurs, control is given to the external exception handler.

You can get the number of elements in a container by using the container's size() member function. For example, the size() function of the vector container returns the number of elements, the size() function of the list container returns the number of elements, the length() function of the string container returns the number of characters, and the capacity() function of the deque container returns the number of allocated memory blocks.

To iterate over an STL container, you can use the container's begin() and end() functions to get the iterator range: Vector: Use a for loop to iterate over the iterator range. Linked list: Use the next() member function to traverse the elements of the linked list. Mapping: Get the key-value iterator and use a for loop to traverse it.

C++ template inheritance allows template-derived classes to reuse the code and functionality of the base class template, which is suitable for creating classes with the same core logic but different specific behaviors. The template inheritance syntax is: templateclassDerived:publicBase{}. Example: templateclassBase{};templateclassDerived:publicBase{};. Practical case: Created the derived class Derived, inherited the counting function of the base class Base, and added the printCount method to print the current count.

C++ templates are widely used in actual development, including container class templates, algorithm templates, generic function templates and metaprogramming templates. For example, a generic sorting algorithm can sort arrays of different types of data.

In multi-threaded C++, exception handling is implemented through the std::promise and std::future mechanisms: use the promise object to record the exception in the thread that throws the exception. Use a future object to check for exceptions in the thread that receives the exception. Practical cases show how to use promises and futures to catch and handle exceptions in different threads.