Question

In a big-endian machine, if I have a long variable and cast it to a char, does the language specification guarantees I will get the least significant bits after the cast?

In other words:

long a = 50;
char b = (char)a;
assert(b == 50); /* Is it true? */

I know this is true for little-endian machines, but what about big-endian?

Answer 1

…the value is unchanged if it can be represented in the destination type (and bit-field width); otherwise, the value is implementation-defined. (§4.7/3).

Since char must be able to accommodate values up to at least 127, the result in this case must be 50.