C/C++ packing signed char into int

Programmer Question

hello

I have need to pack four signed bytes into 32-bit integral type.
this is what I came up to:

int32_t byte(int8_t c) { return (unsigned char)c; }

int pack(char c0, char c1, ...) {
  return byte(c0) | byte(c1) << 8 | ...;
}

is this a good solution? Is it portable (not in communication sense)?
is there a ready-made solution, perhaps boost?

issue I am mostly concerned about is bit order when converting of negative bits from char to int. I do not know what the correct behavior should be.

Thanks

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