Try to compile your code normally as

gcc test.c

If you get default output file a.exe,then go for

gcc test.c -o test.exe

if you have codeblocks installed with mingw as the gcc compiler then follow these steps

1. Right click on my computer -> go to properties -> advance system settings
2. Then make an environment variable named PATH and paste the complete url like program file (x86)/codeblocks/mingw/bin.
3. now open cmd
4. go to the directory where your program is saved.
5. type gcc program_name.c -o program_name.exe to compile the program.
6. run the program by typing program_name

You need to run

Copygcc b.c -o b.exe

Without -o option it'll use the default output executable name which is a.exe on Windows and a.out on *nix systems. You can easily see the a.exe with the dir command

-o file

• Place output in file file. This applies to whatever sort of output is being produced, whether it be an executable file, an object file, an assembler file or preprocessed C code.

• If -o is not specified, the default is to put an executable file in a.out, the object file for source.suffix in source.o, its assembler file in source.s, a precompiled header file in source.suffix.gch, and all preprocessed C source on standard output.

https://gcc.gnu.org/onlinedocs/gcc/Overall-Options.html

For more information read Determining C executable name

Of course you can also run a instead of b

Traditionally, gcc always names the executable "a.out" unless told otherwise.

You should use:

gcc -o gcc_test.exe gcc_test.c

You can probably also use:

make gcc_test