Thread: Huh. int main() acts like char main(). Whoda thunk.

Hello:


(Ubuntu 18.04 gcc version 7.5.0)


Ok... here I thought; "int main()" returned an int. So I tried "return(256)" and bash ($?) reports '0'. "return(255)" reports '255'. Why does main() seem to be limiting to what looks like a CHAR?


And, equally curious, if I try "char main()", the program compiles w/ warning. Using "return('G')" to bash ($?) reports '71', which is decimal for Capital-G.


Recompiling back to int main(), and trying "return(512)" reports '0', and "return(513)" reports '1'. Looks like return(whatever_value % 256) is the behavior.


For my x86_64, using #include <limits.h> reports:


The minimum value of SHORT INT = -32768
The maximum value of SHORT INT = 32767
The minimum value of INT = -2147483648
The maximum value of INT = 2147483647


'Ya learn something every day.......
Thx

main() does return an int, but Linux limits the value to the range, 0 - 255, as specified by GNU here.

Other O/S's might allow a different range.

Originally Posted by Salem

wait(2): wait for process to change state - Linux man page

Scroll down to WEXITSTATUS

Read what it says.

Sorry, I have no idea what this means, or how it applies here. Thx.

Originally Posted by rstanley

main() does return an int, but Linux limits the value to the range, 0 - 255, as specified by GNU here.

Other O/S's might allow a different range.

Well, that's clear enough. I am working on a 'C' tutorial series, and this cropped up unexpectedly. Thx.