Member Avatar for ejptccs123

Hi, I need to have my compiler take preprocessor definitions from the
command line. How does it differ from normal command line parameter passing (main(int arc, char *argv[])) ?
Thanks.

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  • Latest Post Latest Post by thekashyap
Member Avatar for Narue

It depends on the compiler; you'll usually see things like -D<symbol> or \D<symbol>. Look it up in your documentation.

Member Avatar for ejptccs123

Thanks for the tip. I'm using Dev-C++. And I got the preprocessor flag to work.
Thanks.

Member Avatar for paramaguru

i need it fast

Hi, I need to have my compiler take preprocessor definitions from the
command line. How does it differ from normal command line parameter passing (main(int arc, char *argv[])) ?
Thanks.

commented: Digging up a thread from 3 years ago +0
commented: Rude -2
Member Avatar for vijayan121

1. g++ -DHAVE_CONFIG -Wall -std=c++98 -o myprogram
2. ,/myprogram hello world

in 1., the command line args are used by the c preprocessor, some are forwarded to the compiler and linker

in 2., the command line args are passed to myprogram and are available as parameters passed to main

Member Avatar for thekashyap

preprocessor directives/macros are processed at the time of compilation. Arguments relevant to preprocessor (e.g. -DXXX=value) are passed to compiler and used by compiler. Any argument passed on command line is called command line arguments. :). So these are the CLI args to compiler.
After compilation (and linking) the executable of your program is ready.. when you call/execute this executable with CLI args, these would go to main() and will be be available to your program.

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