Pointer In C By Yashwant Kanetkar Pdf Free 29

It's not just about theoretical exotic architectures either. 16-bit compilers for x86 machines provided two kinds of pointers. Near pointers were 16 bits wide and behaved like you'd expect them; however, they only let you access 64k of RAM. If you wanted to access more than 64k of RAM (not 64K for each block: 64K for the whole program!) you had to use far pointers.

Far pointers were 32 bits wide, and made of two 16-bit halves, the segment and the offset; for example 1234:0000 is a pointer that has segment 0x1234 and offset 0. The actual memory address was segment * 16 + offset. Typically, farmalloc returned a pointer with zero offset, and pointer arithmetic only modified the offset. So you could have

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The memory model compiler settings defined whether the default size of pointers was near or far. For example, the "small" memory model had 64K for code and 64K for all of global variables, auto variables (stack) and the malloc heap. Note that the code was in a separate segment, so you couldn't just take a 16-bit ("near") function pointer and dereference it to read machine language! If you had to do that, you had to ask the compiler to put the code in the same segment as the rest (the "tiny" memory model).

The size of code and data was also different, so you could have a memory model where function pointers were near but data pointers were far, or vice versa. This is the case with the aforementioned "compact" model (64K code limit but far pointers for data) and the dual "medium" model (far pointers for code, 64K data limit).

I am learning C. But i am struggling very much in learning the pointers and using them. How you can use pointer instead of an array, also pointers-function. Also pointer of a pointer. All these concepts are keep getting over my head. Please recommand me a book to learn then ao i can have a crystal clear concept. Also if possible a good set of exercises. be457b7860