Re: Fwd: help in the usage of compiling c files

Hello, you should compile object files and then link, like

cc -g -I. -ansi -Wall -pedantic   -c -o image_size.o image_size.c
cc -g -I. -ansi -Wall -pedantic   -c -o readimage.o readimage.c
cc -g -I. -ansi -Wall -pedantic   -c -o jpegll_enc.o jpegll_enc.c
cc -g -o encoder image_size.o readimage.o jpegll_enc.o -L. -lm

this works for me using gcc 7.5 on Linux, then it's better to put (cc is
alias to gcc)
compile commands in a Makefile such:

text file Makefile:

#---------------------------------------------------
TARGET1=encoder
CC=cc -g

SRC = $(wildcard *.c)
OBJ = $(SRC:.c=.o)
CFLAGS = -I. -ansi -Wall -pedantic
LDFLAGS = -L. -lm

TARGETS = $(TARGET1)

$(TARGET1): $(OBJ)
$(CC) -o $@ $^ $(LDFLAGS)

all: $(TARGETS)
echo "done all targets"

.PHONY: clean
clean:
rm -f $(OBJ) $(TARGETS)
#---------------------------------------------------

then you can compile with

make

(log files attached, created with make > out.log 2> err.log )
If you want to compile on mingw you need to change cc with
mingw compiler command.
(i686-w64-mingw32-gcc.exe or x86_64-w64-mingw32-gcc.exe on MS win msys2)
you can also remove warnings putting header files as compiler tips write.

Hope this can help you.

Cheers.
Francesco Lazzarotto.


On Thu, 24 Sep 2020 at 18:45, Aileen Sengupta <[email protected]>
wrote:

>
> ---------- Forwarded message ---------
> From: Aileen Sengupta <[email protected]>
> Date: Mon, 21 Sep 2020, 01:18
> Subject: help in the usage of compiling c files
> To: <[email protected]>
>
>
>
> Dear Team,
>
> I have recently installed the MinGW and I am trying to run the following
> command
> gcc -o encoder jpegll_enc.c idc.h readimage.c image_size.c and I get the
> following error:
>
> [image: image.png]
>
> I have all the necessary files in the same folder as shown in the command
> prompt.
> I have attached the files in the email. I have tried every possible
> solutions and I needed help. Can you help me with the possible solution?
> --
> Thanks and Regards,
> Aileen Sengupta
>
> https://sites.google.com/site/aileensengupta/
> https://in.linkedin.com/in/aileen-sengupta-91547a24
> _______________________________________________
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-- 
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skype:fralaz1971

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cc -g -I. -ansi -Wall -pedantic   -c -o image_size.o image_size.c
cc -g -I. -ansi -Wall -pedantic   -c -o readimage.o readimage.c
cc -g -I. -ansi -Wall -pedantic   -c -o jpegll_enc.o jpegll_enc.c
cc -g -o encoder image_size.o readimage.o jpegll_enc.o -L. -lm

readimage.c: In function ‘readimage’:
readimage.c:39:3: warning: implicit declaration of function ‘exit’ [-Wimplicit-function-declaration]
   exit(1);
   ^~~~
readimage.c:39:3: warning: incompatible implicit declaration of built-in function ‘exit’
readimage.c:39:3: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
readimage.c:33:13: warning: unused variable ‘c’ [-Wunused-variable]
     {int r, c;
             ^
jpegll_enc.c:31:6: warning: return type of ‘main’ is not ‘int’ [-Wmain]
 void main(int argc, char **argv)
      ^~~~
jpegll_enc.c: In function ‘main’:
jpegll_enc.c:47:12: warning: implicit declaration of function ‘getopt’; did you mean ‘getcode’? [-Wimplicit-function-declaration]
   while((c=getopt(argc,argv,"i:o:m:x:y:h"))!=EOF)
            ^~~~~~
            getcode
jpegll_enc.c:38:15: warning: unused variable ‘optind’ [-Wunused-variable]
   extern int  optind;
               ^~~~~~
jpegll_enc.c:37:11: warning: unused variable ‘ifp’ [-Wunused-variable]
     FILE *ifp, *ofp;
           ^~~