How to use C11 standard in Code::Blocks

Question

Like the Title says I need to make code::blocks to work with C11 and I can't figure out how to do it.

I went to settings => compiler settings => Other options and I added -std=c11 and tried also with -std=gnu11, both doesn't seems to work.

I compiled gcc-5.2 and then I changed the default compiler (gcc-4.9) and still no result.

When I try to compile the following program:

#include<stdio.h>

int main(void){
    int arr[] = {0,1,2,3,4};

    for(int i=0;i<5;i++){
        printf("%d ",arr[i]);
    }

    return 0;
}

I get the following:

|6|error: ‘for’ loop initial declarations are only allowed in C99 or C11 mode|

But if I do it in terminal (ubuntu 15.04, 64BIT, gcc-5.2):

./install/gcc-5.2.0/bin/gcc5.2 program.c -o program

Seems to work fine.

My question is, how to make code::blocks to work with c11 ?

Since the GCC 5.x versions run with `-std=gnu11` by default, Code::Blocks must be doing something (such as passing `-ansi` or `-std=gnu90`) to the compiler to make it work differently. Investigate all the options that are sent to the compiler. Find a way to have Code::Blocks show you the exact incantation it uses when compiling. Then work out how to fix it. (I've not used Code::Blocks so I can't be more helpful than that — assuming this is of any help at all.) — Jonathan Leffler, Dec 08 '15 at 18:33
@JonathanLeffler This are the Options that is use =>> `-Wall -Wextra -Werror -Wstrict-prototypes -Wconversion -std=gnu11 -O0 -g -ansi` `pkg-config --cflags gtk+-3.0` — Michi, Dec 08 '15 at 18:33
The `-ansi` is doing the damage; it is equivalent to `-std=c90` or perhaps `-std=gnu90` — it explicitly undoes `-std=c11` or `-std=gnu11`. (And, FYI, you can embed back-quotes in the code block of a comment by using two to start and end and one in the middle: ``-Wall … `pkg-config --cflags gtk+-3.0` `` — like that. — Jonathan Leffler, Dec 08 '15 at 18:34
@JonathanLeffler Thank you, you right, `-ansi` was the problem. I though that i need that option too, I mean `-ansi` — Michi, Dec 08 '15 at 18:36

score 5 · Accepted Answer · edited Jun 20 '20 at 09:12

5

Since the GCC 5.x versions run with -std=gnu11 by default, Code::Blocks must be doing something (such as passing -ansi or -std=gnu90) to the compiler to make it work differently.

Investigate all the options that are sent to the compiler. Find a way to have Code::Blocks show you the exact incantation it uses when compiling. Then work out how to fix it.

Options that are used are:

-Wall -Wextra -Werror -Wstrict-prototypes -Wconversion -std=gnu11 \
-O0 -g -ansi `pkg-config --cflags gtk+-3.0`

The -ansi is doing the damage; it is equivalent to -std=c90 or perhaps -std=gnu90 — it explicitly undoes -std=c11 or -std=gnu11.

edited Jun 20 '20 at 09:12

Community

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answered Dec 08 '15 at 18:40

Jonathan Leffler

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I didn't know, I hope the other Flags are OK. – Michi Dec 08 '15 at 18:41
Yes, though the `-O0` is not one I'd normally use. I routinely use `-O3 -g`. I add some: `-Wmissing-prototypes -Wold-style-definition`, and sometimes add others. Once you lose the `-ansi`, what you've got is workable though possibly a bit sub-optimal (because `-O0` means minimal optimization). – Jonathan Leffler Dec 08 '15 at 18:44
The main reason why I use `-O0` is because of this =>> [Please take a look](http://stackoverflow.com/questions/33412495/why-doesnt-valgrind-spot-the-leak-when-program-was-compiled-with-gcc-5-2-0) – Michi Dec 08 '15 at 18:47
Hmm…interesting. Compile with `-O0` so that even if your program is so simple that GCC can optimize away your memory leaks, they still get spotted because they aren't optimized away. If the memory doesn't leak because the compiler spots that it doesn't need to allocate the memory, is it still a leak? (And does a tree falling in the forest make a sound when there's no-one there to hear it?) It's interesting how sophisticated the optimizer is. I'm not sure I'd go about using `-O0` very often just because of that. Thanks for the x-ref. – Jonathan Leffler Dec 08 '15 at 18:55
I don't think this will work with the default installation of Codeblocks, because it uses an older version of GCC. I installed Codeblocks half a year ago and then I had to manually tell it to use a different GCC. Since this was for Windows, I had to point out the MinGW 64 installation. – Lundin Dec 11 '15 at 09:33
@Lundin: Maybe it won't work with the default installation. The OP indicated he'd switched between GCC 5.2 and 4.9, so he is adept at configuring it. The key point in the answer is that the `-ansi` flag is similar to `-std=c90` and should not be used (or not used after `-std=gnu11`). – Jonathan Leffler Dec 11 '15 at 14:27
@JonathanLeffler Sorry for this late response. You're right. I'm currently running 4 different compiler version (GCC) and I can switch that in code::blocks any time. I can't confirm what Lundin say because is more then 10 years since I used Windows. On Linux you can. – Michi Jul 23 '16 at 09:15

score 3 · Answer 2 · answered Dec 11 '15 at 09:47

Assuming Codeblocks 13.12 for Windows, it comes with an older version of GCC (4.7.1) that doesn't support C11.

Manually download the latest version of the Mingw 64 compiler (I don't think Mingw32 is maintained to include GCC versions of C11).
Install it. It will end up in some obscure folder like C:\Program Files\mingw-w64\x86_64-4.9.1-win32-seh-rt_v3-rev1\mingw64.
Add the above path in Codeblocks, Settings -> Compiler -> Toolchain executables tab -> Compiler's installation directory. Click the "auto detect" button.
In the same tab, check that the C compiler is x86_64-w64-mingw32-gcc.exe (since you now might have multiple installations of GCC on your computer) and that the make program is mingw32-make.exe.
In the tab Compiler settings, right click on the list of compiler flags and select "New flag". For "name" type in C11, for compiler flags type in -std=c11. Click ok and check the new C11 option you just created.
Also to ensure C11 conformance, check the option "treat errors as the warnings demanded by ISO C..." (-pedantic-errors). Check the option "Enable all common compiler warnings" (-Wall).

Thank you for your Answer, it will be good for someone who work with Microsoft (windows) products, but me I'm a Linux user since 2004. I did explain in my Question that I use `ubuntu 15.04, 64BIT, gcc-5.2`. Any way +1 for your Answer. — Michi, Dec 11 '15 at 13:39
@Michi The way of configuring Codeblocks to pick a different compiler & set it to compile according to C11 should be the same in Ubuntu though. Far easier probably, since you don't have to go through the Mingw installation fuss. Anyway, you seem to be adding compiler options in the wrong way, this answer explains how you should set Codeblocks to compile for C11. — Lundin, Dec 11 '15 at 14:35
This `-Wall -Wextra -Werror -Wstrict-prototypes -Wconversion -Wmissing-prototypes -Wold-style-definition -std=c11 -O0 -g ` are my compiler options, but I had used `-ansi` and didn't know that conflicts with `-std=c11`. — Michi, Dec 11 '15 at 15:26

score 3 · Answer 3 · edited Apr 26 '17 at 05:19

Am just a learner (beginner - very new) but I hope this might help (though the thread is old).

(code visible in the image is example 12.2 -- forc99.c from Stephen Prata C Primer Plus)

code_blocks_16.01

I created new flag

Settings -> Compiler -> (under general)Right click on general -> New Flag -> Enter details from image -> Ok After that check the box of the new flag just created. (worked for me)

[If you look in the image there is option for -std=c99 (just above the one I created), You can use that option for c99 support.]

(By the way the gcc version for code::blocks 16.01 mingw 32bit, I use this, is 4.9.2)

score 1 · Answer 4 · answered Sep 27 '17 at 04:54

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Go to Settings-> compiler-> Compiler Flags-> General-> tick the box next to " Have g++ follow the c++11 ISO" DONE!!!

answered Sep 27 '17 at 04:54

Jyoti Yadav

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score 0 · Answer 5 · edited Jan 20 '19 at 12:54

I also faced the same problem in my CodeBlock Project. I am using version CodeBlock Version:17.12.

I fixed with following steps:

Go to Setting -> Copmpiler Tab.
"Global Compiler Settings:" pop is openend.
Check Selected Compiler : " GNU GCC Compiler"
Select "Compiler Flag" Tab.
Select following check boxes:
- Have g++ follow the C++11 ISO C++ language standard
- Have gcc follow the 2011 ISO C language standard
Save the settings.
Now i am able to Complie C++11 code.

Hope it works for you guys as well.

score 0 · Answer 6 · answered Feb 27 '19 at 10:32

0

Go to Settings -> Compiler settings

Make sure global compiler settings on the left tab is selected.

On the right tab, click on Compiler settings tab. Under general, check the box against "Have gcc follow the 1999 ISO C language standard [-std=c99]

answered Feb 27 '19 at 10:32

chandraprakash-dev

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score -2 · Answer 7 · answered Aug 11 '16 at 12:59

-2

The reason is because you are declaring i in for loop. Try separating it like below:

#include<stdio.h>

    int main(void)

        {
            int arr[] = {0,1,2,3,4};
            int i;
            for(i=0;i<5;i++){
                printf("%d ",arr[i]);
            }

            return 0;
        }

It will work. Happy coding:)

answered Aug 11 '16 at 12:59

Ayesha Gupta

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I upvoted you because today I made the same mistake like you now, watching a Code without reading the whole Question. Please read the Question again and do a good answer about it. :) – Michi Aug 11 '16 at 15:27
There is nothing wrong with the code, the question is about C11. Do you even know what C11, or even C99 is? This doesn't answer the question - it is not even related to the question. – Lundin Aug 12 '16 at 07:44

score -3 · Answer 8 · edited Nov 25 '16 at 11:36

-3

go to "setting" -> "compiler", then see the option follow "c++11 ISO inc compiler" setting tab.

enter image description here

edited Nov 25 '16 at 11:36

ddb

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answered Nov 25 '16 at 09:11

Ravi Guru

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OP was asking for C11 – Antti Haapala -- Слава Україні Nov 06 '17 at 04:25

How to use C11 standard in Code::Blocks

8 Answers8

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