Saving size_t as unsigned bytes

Question

I have a variable s of type size_t and a variable buffer of type unsigned char. I wish to save this variable in buffer in network order as 4 bytes. How can I do it?

It is 64-bit system.. How can I check how wide is size_t? I can also save it as `uint32_t` or any type, which will be better for this purpose. `uint32_t` is 4 bytes on 64-bit system, isn't it? — MaMu, Feb 12 '14 at 11:33

score 2 · Answer 1 · edited Feb 12 '14 at 11:49

2

size_t myvar;

myvar = htonl(myvar); // For the endian issues

memcpy(buffer, &myvar, sizeof(size_t));

edited Feb 12 '14 at 11:49

alk

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answered Feb 12 '14 at 11:35

MOHAMED

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score 2 · Accepted Answer · edited May 23 '17 at 12:20

2

char c8[8] = {0};
size_t s = 0x1233456789abcdef0, s_be = 0;

if (4 == sizeof(s))
{
  s_be = htonl(s);
}
else if (8 == sizeof(s))
{
  s_be = htobe64(s);
}
else
{
  assert(0);
}

memcpy(c8, &s_be, sizeof(s_be));

For htobe64() have a look here: https://stackoverflow.com/a/4410728/694576

edited May 23 '17 at 12:20

Community

1
1

answered Feb 12 '14 at 11:40

alk

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For a pedantic solution, how about `32 == sizeof(s)*CHAR_BIT` or `sizeof(uint32_t) == sizeof(s)`? – chux - Reinstate Monica Oct 31 '14 at 19:01

Saving size_t as unsigned bytes

2 Answers2