Programming Fundamentals

SIGNAL operation increments the semaphore value, potentially waking up waiting processes. WAIT decrements it. These are the two primitive semaphore operations used for inter-process synchronization.

A binary semaphore can only take values 0 and 1, acting like a mutex lock. It's used for mutual exclusion. General (counting) semaphores can take non-negative integer values and manage multiple resource instances.

In programming, functions can return various data types including primitive values (numbers, strings, booleans) and complex objects. Objects are a valid return type in languages like JavaScript, Python, and many others.

Inline functions eliminate the function call and return overhead by replacing the call site with the actual function body at compile time. This avoids stack frame creation, parameter passing, and jump instructions, which can improve execution speed for small, frequently called functions.

In C++, default arguments must be specified from right to left. If a parameter has a default value, all parameters to its right must also have default values. Here, parameter 'a' has a default value but parameter 'b' (to its right) does not, making this declaration invalid.

Union is a user-defined data type that allows different data types to share the same memory location. Arrays and pointers are built-in types provided by the language, while functions are program constructs, not data types. Union, along with struct, enum, and class, must be defined by the programmer before use.

Assignment D (*p=&i) is invalid. The left side *p dereferences the pointer to access the integer value it points to, while &i gives the address of i. You cannot assign an address to an integer value. Assignments A and B require p to point to valid memory first, and C correctly stores i's address in p.

During function calls, the sequence (order) of actual and formal parameters must match exactly. You cannot rearrange the order of arguments - the first actual parameter maps to the first formal parameter, the second to the second, and so on. This is why option A is the incorrect statement.

The variables passed to a function during a function call are called actual parameters (or actual arguments). They are the values or expressions provided by the caller. Formal parameters are the variables declared in the function definition that receive these values. Local and global variables are storage duration specifiers, not call-related terms.

In most programming languages including C/C++, functions can only return exactly one value. While there are workarounds like returning pointers/arrays or using reference parameters, the formal return statement itself returns only one value. This is a fundamental limitation.

C++ allows variables to be declared anywhere in the program, not just at the beginning of a block. This is a key difference from C89. Variables can be declared at their point of first use, which improves code readability and allows initialization closer to where values are needed.

In linked lists, a null pointer (NULL in C/C++) marks the end of the list. When traversing, encountering a null next pointer signals there are no more nodes to follow. This is different from an empty list (where the head pointer itself is null) or an empty structure field.

To access a structure member through a pointer, you must dereference the pointer first before applying the dot operator. (*p).mem correctly dereferences p to get the structure, then accesses mem. The shorthand p->mem is equivalent and more commonly used. *p.mem would try to dereference a non-existent p.mem, and *(p.mem) is invalid.