C- Readline() undefined reference

Question

i am trying to run this code but the compiler fails : undefined reference to ' readline ' and undefined reference to ' add_history ' .I am using CodeBlocks .This is my code :

#include <stdio.h>
#include <stdlib.h>

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

int main()
{
    char *buf;



    while((buf = readline("\n >> "))!=NULL)
    {
        if (strcmp(buf,"quit")==0)
            break;

        printf("[%s]\n",buf);

        if (buf[0]!=0)
            add_history(buf);
    }

    free(buf);

    return 0;
}

Add the `readline` folder to your search path, and then `#include ` See also http://stackoverflow.com/a/12563042 — Robert Harvey, Dec 15 '14 at 21:47
If you want to reference a project file, you enclose its name with `"..."` not with `<...>` the latter references the compiler library. — Weather Vane, Dec 15 '14 at 21:53
Ah, true. See https://gcc.gnu.org/onlinedocs/cpp/Include-Syntax.html and http://stackoverflow.com/questions/21593 — Robert Harvey, Dec 15 '14 at 21:55
@RobertHarvey `undefined reference` has nothing to do with includes. — Iharob Al Asimi, Dec 15 '14 at 21:57
`readline()` is not a C standard library function. So you have to include the library it's in and any header files needed, as well as tell the linker where to find it. — Lee Daniel Crocker, Dec 15 '14 at 21:57
This is what i done , but still same thing : #include "/home/myname/Downloads/readline-6.3/readline.h" #include — Angelo, Dec 15 '14 at 22:00
what is the platform you work with? e.g. in ubuntu you might need to have `libreadline6-dev` and `libreadline6` installed, and to compile your code with `-lreadline` — lp_, Dec 15 '14 at 22:02
I am using Ubuntu . I tried to install it , when i do 'make install' , it tries to put the readline in the include folder and it gives an error : persmission denied, so it fails — Angelo, Dec 15 '14 at 22:06
You do not, I repeat, not install software from sources. Do not invoke `./configure && make && make install`, do not pass go. Install packages from the repository using your package manager. — n. m. could be an AI, Dec 15 '14 at 22:38

Iharob Al Asimi · Accepted Answer · 2014-12-15T22:16:55.753

1

Ok, just ensure the development files for readline are installed for which you need to run this as the root user

# apt-get install libreadline-dev

as someone mentioned in the comments.

Next, you go to the Project->Build Options menu and a dialog pops up Build Options Dialog

then go to the Linker Settings tab Linker Settings Tab

now just click the Add button, and type readline in the dialog that pops up enter image description here

click Ok, and try building now, it should work.

edited Dec 15 '14 at 22:16

answered Dec 15 '14 at 21:59

Iharob Al Asimi

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C- Readline() undefined reference

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