I want to enter some command line arguments at run time. Like
./program abc def ghi
argc would be 4 in this case. No problem in this. But if I do
./program abc def *
or even
./program * abc def
the variable argc gives me a value far larger than 4.
On printing the entire argv array (leaving aside the 0th argument; ./program) as strings, I am given a list where the first two elements are abc and def and the others are all file names of the files contained in the working directory.
I am trying to learn C from K&R. I was trying to make an RPN calculator where we can give expressions like ./program 2 4 *.
What is the reason for this? Or am I wrong somewhere?
Shells have a feature called globbing, where they expand certain patterns, such as * to the matching files. If in the current directory you have the following:
file1 file2 somethingelse dir1
then calling:
any_program *
will be equivalent to:
any_program file1 file2 somethingelse dir1
Or if you do:
any_program fi*
it will be equivalent to:
any_program file1 file2
This is a feature of the shell. Your C program is well-behaved.
Since shells are different, let's assume you are using bash. To prevent bash from performing expansions, you should quote the argument. For example:
any_program "fi*"
will actually pass fi* to your program, without expanding it to file1 file2.