You are to write two C methods to extract and insert bytes into an int. The firs

Question

You are to write two C methods to extract and insert bytes into an int.
                    
                    The first is called GetNthByte that will take two arguments Value and ByteNdx, where ByteNdx is 0,1,2, or 3.
                    
                    The prototype for GetNthByte is
                    unsigned char GetNthByte (int Value, int ByteNdx);
                    
                    GetNthByte will return the byte specified by ByteNdx as we count the bytes from low to high 0 , 1, 2, 3.
                    Thus
                    GetNthByte(0xFACECAFE, 2) will return 0XCE, and NthByte(0xFACECAFE, 1) will return 0XCA.
                    
                    PutNthByte will return a newly created value created by putting a new byte into the byte specified by ByteNdx, again as we count the bytes from low to                     high 0 , 1, 2, 3.
                    
                    The prototype for PutNthByte is
                    unsigned int PutNthByte (int Value, int ByteNdx, unsigned char NewByte);
                    
                    Use the %x                     format descriptor for output.
                    
                    Some interesting possible cases to try for GetNth and PutNth
                    
                    Value ByteNdx NewByte
                    -1 2 0xA
                    0xDEADBEEF 3 'A'
                    2^32 - 1 2 0
                    127 3 0xF

Explanation / Answer

For the (n+1) byte:

int x = ((unsigned char *)(&number))[n];

For the (n+1)th byte from least to most significant on big-endian machines:

int x = ((unsigned char *)(&number))[sizeof(int) - 1 - n];

For the (n+1)th byte from least to most significant (any endian):

int x = ((unsigned int)number >> (n << 3)) & 0xff;

Of course, these all assume that n < sizeof(int), and that number is an int

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