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What is the size of null pointer?
A NULL pointer has the same size as a non NULL pointer. NULL means that the pointer has been set to the NULL value that is usually zero (0) but the NULL value is at the digression of the compiler manufacture (and may have a value other than zero) so a pointer should always be set to the NULL value and not zero. Current compilers (32 and 64 bit, Intel chip) have a pointer size of 4 (8 bit) bytes. It should be noted that the number of bits in any data type is at the compiler manufactures digression but is heavily influenced by the computer hardware. void *p= NULL; printf ("%d\n", sizeof (p)); or printf ("%d\n", sizeof (void *));
What kind of information is represented by a pointer variable?
It is variable. On most PCs it is either 32 or 64 bits. But it can be smaller on other systems. To find the size use sizeof(void*) .
Explain pointer of any data type that requires four bytes?
When a pointer to a data type that requires four bytes is declared, the compiler knows that the target object is four bytes in size. When the program then performs a calculation to offset the pointer, such as to add 3 (for instance) to the pointer, the generated code actually adds 12. This is because the compiler assumes that adding or subtracting numbers to or from a pointer is an attempt to use the pointer in an array context. (Actually, this behavior is defined in the language specification.)The other valid arithmetic manipulation of a pointer is subtraction of two pointers to the same type of object. In this case, again, an internal multiplier of 4 is applied, and the result is an offset that could be used if the first pointer were the base of an array of those objects.The size of the target object could be any value, such as a double which might be 8 bytes. The compiler will do the arithmetic correctly.Also, keep in mind the distinction between the size of the pointer and the size of the object to which the pointer points. This answer assumes the latter.In any case, the programmer must insure that the calculation results in a pointer or offset value that represents an address in the base object array, assuming that the allocated space of that object is correct. Any other result is inconsistent with the defined usage of a pointer, and the result of dereferencing such an inconsistent pointer or offset is undefined by the language specification, and could result in corruption, incorrect behavior, or crash.
What is the difference between initialisation and definition in C programming?
Variable-declaration is: extern int x; extern double y; extern char a; Variable-definition is: int x; static double y; auto char a; Variable-definition with initialization is: int x = 1; static double y= 2.3; auto char a = 'w';
What is the maximum integer allowed in an integer-type variable?
That varies from each programming language. As a matter of fact, many languages do not put a limit on the maximum size of a variable. It will handle any string, integer, resource, pointer, or other type size, as long as it fits into the memory of the machine running the process.
