C program using double pointers

In the case of the last node in the list, the next field contains NULL - it is set as a null pointer. Our nodes are defined with a C struct - for the purposes of this exercise, nodes are defined as NODE using typedef.

A pointer is a variable that stores the memory address of another variable. In C, you need to define the type of the object that is being pointed at. The variable pNum now contains the address of a , which is the memory location of an object having the data type integer. In this way, head becomes the access point for sequential access to the list.

As the first node is added, the head pointer is amended to point to the new node, and the next pointer of the new node points to NULL. In the case of the first node, append and prepend have exactly the same effect. Arguments are always passed to functions by value in C.

In other words, when C passes control to a function, a copy of each argument is made and this copy is passed to the function - leaving the original variable unchanged. In order to amend a variable in a calling function from within a called function, you need to pass a pointer to the variable as a function argument. This provides the called function with the memory address of the variable to be amended.

C for Loop. Arrays in C Programming. Pointers in C. Find roots of a quadratic equation. Print Pyramids and Patterns. Check prime number. Print the Fibonacci series. Reference Materials string. Start Learning C. Explore C Examples. C Pass Addresses and Pointers. Access Array Elements Using Pointer.

C Dynamic Memory Allocation. C Array and Pointer Examples. C Pointers In this tutorial, you'll learn about pointers; what pointers are, how do you use them and the common mistakes you might face when working with them with the help of examples. Let us see how this exactly works by below example and pictorial form:. This can be shown as. In this article, let us see why and where double pointers can be used.

There are several uses of a pointer to pointer where it is the address of a data. This can be explained by writing this code. Another use of a double pointer is when we want to allocate space in the matrix. This can be explained in the below code. Therefore, in the same way, a pointer to an integer pointer can have the starting address in the array of an integer as that is also an integer.

Double pointers can also be used when we want to alter or change the value of the pointer. As we did it in the previous code. Let us consider an example where we want to change or update a character from a function. The above code will not execute as we have passed the value to the function so this can be done by using pointers while passing by reference.

In this article, we can conclude that pointers are also variables that can store values.