Hi all,

I've bought the book "Objective-C Programming - The Big Nerd Ranch Guide" and I'm running through the beginning chapters which just regard C.

I'm doing this on my laptop running linux as I don't have a Mac (yet).

I'm having trouble with this code:

#import <stdio.h>
#include <readline/readline.h>
#include <readline/history.h>

int main(int argc, char * argv[]) {

    printf("Who is cool? ");
    const char *name = readline(NULL);
    printf("%s is cool!\n\n", name);

    return 0;
}

I'm compiling (attempting to) using this command:

gcc -lreadline -o Coolness main.c // "Coolness" being the name of the program in the book

I'm getting the following error when trying to compile:

main.c:1:2: warning: #import is a deprecated GCC extension [-Wdeprecated]
/tmp/ccjLJXtd.o: In function main': main.c:(.text+0x1d): undefined reference toreadline'
collect2: error: ld returned 1 exit status

I've been trying to look up a solution but have so far only managed to get as far as the compile command above, grabbing the readline includes and adding #include <readline.h> and <history.h> (though I'm not sure what history.h is for or if I need it).

Any assistance would be greatly appreciated.

Thanks

Your computer is probably missing the readline folder and associated header files and library files.

Edited 2 Years Ago by Ancient Dragon

If you are trying to learn objective-c, are you sure you install the gcc-objc (objective-C) compiler/package on your system? Also, try replacing the line #import <stdio.h> with #include <stdio.h>

Edited 2 Years Ago by rubberman

Ancient Dragon: The files were missing initially but I've installed them since. Otherwise the error would be along the lines of "readline.h doesn't exist/not found/ etc..."
rubberman: Yeah, I'd noticed that about import but it's just a warning so I'm ignoring it. The book used it so I went with it :)
The work I'm doing currently is just for C so I wouldn't have thought that I would need an Objective-C compiler for this part.
By the end of the week I'll have a Mac Mini and let XCode worry about linking libraries.

but it's just a warning so I'm ignoring it.

You should never ignore warnings (except maybe in compiler-supplied header files) because 90% of the time they are really errors.

You should never ignore warnings (except maybe in compiler-supplied header files) because 90% of the time they are really errors.

Good advice. Thanks.

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