Question

// Declaration of data type where 4 bytes are packed into an unsigned.   
int xbyte(packed_t word, int bytenum);

int main()
{
    int bytenum = 0;
    typedef unsigned packed_t;
    packed_t word;
}

// Extract byte from word, return as signed integer.
int xbyte(packed_t word, int bytenum)
{
    // Failed attempt at xbyte
    return ( word >> (bytenum << 3)) & 0xff;
}

I am unsure how to declare the packed_t in this question. I am supposed to use the prototype from the top. How does word even come into play. I am lost this is part of a homework assignment.

Answer 1

You already have a typedef line. Make it the first line of this piece of code, and you are done. The basic thing is that the typedefed name must be visible everywhere you use it.