21 Dec 2024

Preventing Form Submission on Remove Button ClickIn the provided HTML form, the "remove" button triggers form submission when clicked. To prevent...

05 Aug 2025

First create a static library: 1. Write the header file math_utils.h declare function; 2. Write the implementation file math_utils.cpp to define function; 3. Use g -c to compile as target file; 4. Package it as libmatutils.a with arrcs; then use static library: 5. Include the header file in main.cpp and call the function; 6. Use g main.cpp-L.-lmathutils link library to generate an executable file; finally run the program outputs are 3 4=7 and 3*4=12. The static library is embedded in the executable file at compile time without external dependencies.

08 Aug 2025

Use static methods when accessing instances or class properties is not required, which acts as a standalone helper function in the class for logically related but stateless operations. 1. The static method is decorated with @staticmethod and does not receive self or cls parameters; 2. It can be called directly through the class name without instantiation; 3. It is suitable for general logic such as tool functions or data verification, such as judging whether age is adult; 4. Unlike instance methods and class methods, static methods cannot access instances or class data; 5. The main advantage is to improve the organization and readability of the code, which is suitable for scenarios that do not depend on the state of the object.

06 Aug 2025

The static local variables in the function are only initialized once and the life cycle runs throughout the program; 2. The static global variables or functions in the file scope have internal links and are only accessible to this file; 3. The static member variables in the class are shared by all objects and must be defined outside the class; 4. The static member function in the class does not depend on object instances, can only access static members, and can be called directly through the class name.

21 Aug 2025

static_assert is used to check constant expressions at compile time. If the condition does not hold, a compilation error will be triggered and a prompt message will be displayed. 1. Can be used to check the type size, such as static_assert(sizeof(int)==4,"intmustbe4bytes"); 2. Verify type constraints in the template, such as static_assert(std::is_integral::value,"Tmustbeanintegraltype"); 3. Verify the compilation period calculation results, such as static_assert(factorial(5)==120

18 Nov 2024

AngularJS Button Within Form Triggers Page RefreshThis issue arises when you have a form with both a submit button and a navigation button. Upon...

28 Jul 2025

When using sync.Mutex to protect shared variables, it is necessary to lock and unlock before and after accessing the variables to ensure data consistency; 2. It is recommended to encapsulate Mutex and data in a structure to control access through methods to prevent external bypassing the lock mechanism; 3. In scenarios where more reads and fewer writes, sync.RWMutex should be used to improve concurrency performance and allow multiple read operations to be performed simultaneously; 4. Copying structures containing Mutex should be prohibited, and instances should be shared through pointers; 5. Always use defermutex.Unlock() to avoid deadlocks or resource leakage; 6. Avoid calling external functions or inconsistent lock orders during lock holding. Proper use of these patterns can effectively prevent data competition and improve program stability.

09 Apr 2025

The <p>GroupBy Having clause is used to filter grouped data. It first groups the data and then filters the results according to the specified conditions. Common usages include: </p><ol><li>Find out the sum or average of a specific group. </li><li>Find groups that meet certain criteria. </li><li>Aggregate the grouped data, such as summing, average or counting. </li></ol>

26 Oct 2024

HTML Button to Resist Form SubmissionQuestion:How can one create a button outside an HTML form that does not submit the form when clicked?Consider...