C Language Interview Questions

In C, null is a macro that represents a null pointer constant, which is typically defined as either 0 or (void*)0, while undefined is not a valid concept in C as it is in other languages, and using an uninitialized variable will result in undefined behavior.

To implement a singly linked list in C, you need to define a structure for the list node, which contains data and a pointer to the next node, then create functions for inserting nodes at the beginning and end of the list, deleting nodes, and traversing the list.

The malloc function in C is used to dynamically allocate memory, which means it reserves a block of memory of a specified size and returns a pointer to the beginning of that block, allowing you to manually manage memory for your program.

In C, you can handle errors by checking the return values of functions, such as fopen, malloc, and fscanf, which return NULL or a negative value to indicate an error, and then use error-handling functions like perror or fprintf to print error messages and exit the program if necessary.

In C, pass-by-value means that when you pass a variable to a function, a copy of the variable's value is made and passed to the function, so changes to the variable within the function do not affect the original variable, while pass-by-reference means that you pass a pointer to the variable, allowing the function to modify the original variable.