CODEWITHSUNDEEP
cshellgccarguments
İhsan Cemil Çiçek
İhsan Cemil Çiçek

Reputation: 301

C passing other c program as main argv

Just a curiosity,

Consider that I have

./first

./second

that they are executable c program

first.c:

char main(void){
    return '5';
}

second.c:

#include<stdio.h>
int main(int argc, char** argv){
    printf("%s", argv[2]);
    return 0;
}

(I want to print 5 here)

Is it possible to compile second.c like:

gcc second.c -./first

Of course I know that wont work but is it possible to write something that will work like what I want?

Upvotes: 2

Views: 53

Answers (2)

dbush
dbush

Reputation: 223917

Have the first program print "5":

int main(void){
    printf("5\n");
    return 0;
}

Then you can use backquotes in the shell to put the output of this program into the parameters of the other:

./second `./first`

Upvotes: 0

Barmar
Barmar

Reputation: 781004

The return value of main() becomes the program's exit status, which is put in the shell's $? variable. So it should be:

./first
./second $?

You should change first.c to return an int, not char; otherwise it will print the ASCII code for the '5' character, not 5.

int main(void){
    return 5;
}

And in second.c, it should be argc[1], not argv[2].

Upvotes: 2

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