HowTo Compile a 32-bit Application Using gcc On the 64-bit Linux Version

I had to compile a 32-bit application using GNU gcc on the 64-bit version of Linux.

Luckily, gcc man page directed me to the '-m32' and '-m64' options. These options generate code for 32-bit or 64-bit environments, respectively.

1. The 32-bit environment sets int, long and pointer to 32 bits and generates code that runs on any i386 system.
2. The 64-bit environment sets int to 32 bits and long and pointer to 64 bits and generates code for AMD's x86-64 architecture.

You can pass -m64 or -m32 options as follows to Gnu gcc

For 32 bit version:
$ gcc -m32 -o output32 hello.c
For 64 bit version :
$ gcc -m64 -o output64 hello.c
Run it as follows:
$ ./output32
Output:

Long int size is 4 bytes long!

Now let us see 64 bit output:
$ ./output64

Long int size is 8 bytes long!

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Thank you
Rajesh
srajeshinfotech.blogspot.com