Not only multiplying, even addition and division are also not allowed in pointers. The only operation you can do is subtraction, if both the pointers are of same type.

You have noticed that, I haven’t used any & (address of) operator in the scanf() function. scanf() takes the actual memory address where the user input is to be stored. The pointer variable ptr1 and ptr2 contains the actual memory addresses of num1 and num2.

The program output is also shown below.

1. * C program to read N integers and store them in an array A.
2. * Find the sum of all these elements using pointer.
3. #include
4. int i, n, sum = 0;
5. int *a;
6. printf(“Enter the size of array A /n”);
7. scanf(“%d”, &n);
8. a = (int *) malloc(n * sizeof(int));

Pointers contain addresses. Adding two addresses makes no sense, because you have no idea what you would point to. Subtracting two addresses lets you compute the offset between these two addresses, which may be very useful in some situations.

C Programming: Tips of the Day

1. Static function in C.
2. helper_file.c intf1(int); /* prototype */ staticintf2(int); /* prototype */ intf1(int foo){ return f2(foo); /* ok, f2 is in the same translation unit */ /* (basically same .c file) as f1 */ } intf2(int foo){ return42 + foo; }

Structure is a user-defined datatype in C language which allows us to combine data of different types together. Structure helps to construct a complex data type which is more meaningful. It is somewhat similar to an Array, but an array holds data of similar type only. In structure, data is stored in form of records.

There are three basic types of structures: shell structures, frame structures and solid structures.

Array refers to a collection consisting of elements of homogenous data type. Structure refers to a collection consisting of elements of heterogenous data type. Array is pointer as it points to the first element of the collection. Structure is a user-defined datatype.

How to declare structure variables? A structure variable can either be declared with structure declaration or as a separate declaration like basic types. // A variable declaration with structure declaration. Note: In C++, the struct keyword is optional before in declaration of a variable.

Structure is a group of variables of different data types represented by a single name. Lets take an example to understand the need of a structure in C programming. Lets say we need to store the data of students like student name, age, address, id etc. We can solve this problem easily by using structure.

Basically structure of the C program is divided into six different sections, Documentation section: The Documentation section consists of a set of comment lines. Link section: The link section provides instruction to the compiler to link the header files or functions from the system library.

Create struct variables When a struct type is declared, no storage or memory is allocated. To allocate memory of a given structure type and work with it, we need to create variables. Another way of creating a struct variable is: struct Person { char name[50]; int citNo; float salary; } person1, person2, p[20];

CProgrammingServer Side Programming. Enumeration is a user defined datatype in C language. It is used to assign names to the integral constants which makes a program easy to read and maintain. The keyword “enum” is used to declare an enumeration.

An enum type is a special data type that enables for a variable to be a set of predefined constants. The variable must be equal to one of the values that have been predefined for it. Common examples include compass directions (values of NORTH, SOUTH, EAST, and WEST) and the days of the week.

“extern” keyword is used to extend the visibility of function or variable. By default the functions are visible throughout the program, there is no need to declare or define extern functions. It just increase the redundancy. Variables with “extern” keyword are only declared not defined.

In the C programming language, register is a reserved word (or keyword), type modifier, storage class, and hint. If possible, depending of type of CPU and complexity of the program code, it will optimize access to that variable, and will hence improve the execution time of a program.

the extern keyword is used to extend the visibility of variables/functions. Since functions are visible throughout the program by default, the use of extern is not needed in function declarations or definitions. Its use is implicit. When extern is used with a variable, it’s only declared, not defined.

static means a variable will be globally known only in this file. extern means a global variable defined in another file will also be known in this file, and is also used for accessing functions defined in other files. A local variable defined in a function can also be declared as static .

Static variables. Thus, prefixes “ extern ” and “ static ” cannot be used in the same declaration. They maintain their value throughout the execution of the program independently of the scope in which they are defined.

Overview. An array is a collection of data items, all of the same type, accessed using a common name. A one-dimensional array is like a list; A two dimensional array is like a table; The C language places no limits on the number of dimensions in an array, though specific implementations may.

Static variables can be defined inside or outside the function. They are local to the block. The default value of static variables is zero. The static variables are alive till the execution of the program.

Static is a keyword used in C programming language. An ordinary variable is limited to the scope in which it is defined, while the scope of the static variable is throughout the program.

1) A static int variable remains in memory while the program is running. A normal or auto variable is destroyed when a function call where the variable was declared is over. For example, we can use static int to count a number of times a function is called, but an auto variable can’t be used for this purpose.

In the C programming language, static is used with global variables and functions to set their scope to the containing file. In local variables, static is used to store the variable in the statically allocated memory instead of the automatically allocated memory.

When static keyword is used, variable or data members or functions can not be modified again. It is allocated for the lifetime of program. Static variables are initialized only once. …

A null pointer is a pointer which points nothing. Some uses of the null pointer are: a) To initialize a pointer variable when that pointer variable isn’t assigned any valid memory address yet.