On Fri, 2021-06-04 at 08:13 +0000, David Laight wrote: > From: Alex Elder > > Sent: 03 June 2021 22:55 > ... > > Not necessarily, sizeof(bool) is implementation defined. > > And I thought you didn't think the size of the structure > > was very important... > > It is 'implementation defined' but will be 32 bits on everything > except an old 32bit ARM ABI. Really? (x86-64) $ gcc -x c - #include <stdio.h> #include <stdlib.h> struct foo { _Bool b; }; int main(int argc, char **argv) { printf("sizeof _Bool: %zu\n", sizeof(_Bool)); printf("sizeof struct foo: %zu\n", sizeof(struct foo)); return 0; } $ ./a.out sizeof _Bool: 1 sizeof struct foo: 1