Coding Without Tears: Learning C the Easy Way

InstallaC compilerlikeg usingpackagemanagersordevelopmenttoolsdependingontheOS.2.WriteaC programandsaveitwitha.cppextension.3.Compiletheprogramusingg hello.cpp-ohellotogenerateanexecutable.4.Runtheexecutablewith./helloonLinux/macOSorhello.exeonWi

Custom allocator can be used to control the memory allocation behavior of C containers. 1. The LoggingAllocator in the example implements memory operation logging by overloading allocate, deallocate, construct and destroy methods; 2. The allocator needs to define value_type and rebind templates to meet the STL container type conversion requirements; 3. The allocator triggers log output during construction and copying, which is convenient for tracking the life cycle; 4. Actual applications include memory pools, shared memory, debugging tools and embedded systems; 5. Since C 17, construct and destroy can be processed by std::allocator_traits by default

Use the std::system() function to execute system commands, which need to include header files and pass in C-style string commands, such as std::system("ls-l"), and the return value is -1, which means that the command processor is not available.

Create a project directory structure, including CMakeLists.txt, src/ and include/; 2. Write CMakeLists.txt, specify the CMake version, project name, C standard and add executable files; 3. Use mkdirbuild to enter the directory and run cmake.. and cmake--build. for compilation; 4. Add multiple source files through add_executable, and use target_include_directories to include the header file path; 5. Use find_package to find external libraries and link with target_link_libraries; 6.

An abstract class is a class containing at least one pure virtual function. It cannot be instantiated and must be inherited as a base class. The derived class needs to implement all its pure virtual functions, otherwise it will still be an abstract class. 1. Pure virtual functions are declared by virtual return type function name()=0; to define interface specifications; 2. Abstract classes are often used for unified interface design, such as area(), draw(), etc., to implement polymorphic calls; 3. Virtual destructors must be provided for abstract classes (such as virtual~Shape()=default;) to ensure that derived class objects are correctly released through base class pointers; 4. After the derived class inherits, pure virtual functions must be rewrite, such as Rectangle and Circle to implement area() to calculate their respective areas; 5.

C's stack is a container adapter in STL. It follows the principle of back-in-first-out and must include header files; add elements by push, pop removes the top element, and top accesses the top of the stack. Before the operation, check whether it is empty, which is often used in scenarios such as expression evaluation and backtracking.

Theautokeywordletsthecompilerdeducevariabletypesfrominitializers,reducingverbosityandimprovingmaintainability.Itsimplifiescodewithcomplextypeslikeiteratorsandlambdas,supportsreferencesandconstqualifierstoavoidunnecessarycopies,andadaptsautomaticallyw

The answer is to define a class that contains the necessary type alias and operations. First, set value_type, reference, pointer, difference_type and iterator_category, then implement dereference, increment and comparison operations. Finally, provide begin() and end() methods in the container to return the iterator instance, making it compatible with STL algorithms and range for loops.