Functions are the basic unit of organizing code in C, used to realize code reuse and modularization; 1. Functions are created through declarations and definitions, such as intadd(inta,intb) returns the sum of the two numbers; 2. Pass parameters when calling the function, and return the result of the corresponding type after the function is executed; 3. The function without return value uses void as the return type, such as voidgreet(stringname) for outputting greeting information; 4. Using functions can improve code readability, avoid duplication and facilitate maintenance, which is the basic concept of C programming.

decltype is a keyword used by C 11 to deduce expression types at compile time. The derivation results are accurate and do not perform type conversion. 1. decltype(expression) only analyzes types and does not calculate expressions; 2. Deduce the variable name decltype(x) as a declaration type, while decltype((x)) is deduced as x due to lvalue expression; 3. It is often used in templates to deduce the return value through tail-set return type auto-> decltype(t u); 4. Complex type declarations can be simplified in combination with auto, such as decltype(vec.begin())it=vec.begin(); 5. Avoid hard-coded classes in templates

C folderexpressions is a feature introduced by C 17 to simplify recursive operations in variadic parameter templates. 1. Left fold (args...) sum from left to right, such as sum(1,2,3,4,5) returns 15; 2. Logical and (args&&...) determine whether all parameters are true, and empty packets return true; 3. Use (std::cout

C's range-basedfor loop improves code readability and reduces errors by simplifying syntax. Its basic structure is for(declaration:range), which is suitable for arrays and STL containers, such as traversing intarr[] or std::vectorvec. Using references (such as conststd::string&name) can avoid copy overhead and can modify element content. Notes include: 1. Do not modify the container structure in the loop; 2. Ensure that the range is effective and avoid the use of freed memory; 3. There is no built-in index and requires manual maintenance of the counter. Mastering these key points allows you to use this feature efficiently and safely.

ABinarySearchTree(BST)isabinarytreewheretheleftsubtreecontainsonlynodeswithvalueslessthanthenode’svalue,therightsubtreecontainsonlynodeswithvaluesgreaterthanthenode’svalue,andbothsubtreesmustalsobeBSTs;1.TheC implementationincludesaTreeNodestructure

Calling Python scripts in C requires implementation through PythonCAPI. First, initialize the interpreter, then import the module and call the function, and finally clean up the resources; the specific steps are: 1. Initialize the Python interpreter with Py_Initialize(); 2. Load the Python script module with PyImport_Import(); 3. Obtain the objective function through PyObject_GetAttrString(); 4. Use PyObject_CallObject() to pass parameters to call the function; 5. Call Py_DECREF() and Py_Finalize() to release the resource and close the interpreter; in the example, hello is successfully called

References are alias for variables, which must be initialized at declaration and cannot be rebinded. 1. References share the same memory address through alias. Modifying any name will affect the original value; 2. References can be used to achieve bidirectional transmission and avoid copy overhead; 3. References cannot be empty and have the grammar, and do not have the ability to repoint compared to pointers; 4. ConstT& can be used to safely pass parameters, prevent modification and support binding of temporary objects; 5. References of local variables should not be returned to avoid dangling reference errors. Mastering citations is the key foundation for understanding modern C.

std::deque is a sequence container that supports efficient insertion and deletion at both ends. 1. Push_front/pop_front and push_back/pop_back operations can be used in the head and tail; 2. Support random access and subscript modification, but the memory is not continuous, and the &dq[0] cannot be used as a C array; 3. Elements can be added and deleted at any position through insert and erase, but the intermediate operation efficiency is low; 4. Suitable for sliding windows, BFS, double-end buffering and other scenarios; 5. Custom types can be stored, and it is necessary to pay attention to the possible failure of iterators; in short, when it is necessary to frequently add and delete elements at the beginning and end without requiring continuous memory, std::deque is better than vector