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.

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.

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.

Real-time systems require deterministic responses, because correctness depends on the result delivery time; hard real-time systems require strict deadlines, missed will lead to disasters, while soft real-time allows occasional delays; non-deterministic factors such as scheduling, interrupts, caches, memory management, etc. affect timing; the construction plan includes the selection of RTOS, WCET analysis, resource management, hardware optimization and rigorous testing.

AstaticvariableinC retainsitsvaluebetweenfunctioncallsandisinitializedonce.2.Insideafunction,itpreservesstateacrosscalls,suchascountingiterations.3.Inaclass,itissharedamongallinstancesandmustbedefinedoutsidetheclasstoavoidlinkingerrors.4.Staticvaria

Use std::ifstream and std::istreambuf_iterator to efficiently read the entire contents of the file to strings, including spaces and line breaks, and is suitable for medium-sized text files.