compiler shouts an error with the make file
After a certain attempt to write a simple program with a main and one function,
I ask for your help to find the bug. I include the 3 files that are in action:
- the main function in
base.c
- the function in
fun.c
- the
makefile
The compiler says that the function is called in a bad way in the main:
undefined reference to `fun'
base.c
#include <stdio.h>
int fun(char c);
main()
{
printf("please enter a single charn");
char c=getchar();
fun(c);
return 0;
}
fun.c
#include <stdio.h>
int fun(char c)
{
printf("%d3 is the value of your char!n", 'c');
return 0;
}
makefile
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -g -Wall -ansi fun.c -o fun.o
c makefile
edited Nov 24 '18 at 17:49
Jonathan Leffler
569k916821032
asked Nov 24 '18 at 17:30
davidkudavidku
94
add a comment |
After a certain attempt to write a simple program with a main and one function,
I ask for your help to find the bug. I include the 3 files that are in action:
- the main function in
base.c
- the function in
fun.c
- the
makefile
The compiler says that the function is called in a bad way in the main:
undefined reference to `fun'
base.c
#include <stdio.h>
int fun(char c);
main()
{
printf("please enter a single charn");
char c=getchar();
fun(c);
return 0;
}
fun.c
#include <stdio.h>
int fun(char c)
{
printf("%d3 is the value of your char!n", 'c');
return 0;
}
makefile
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -g -Wall -ansi fun.c -o fun.o
c makefile
edited Nov 24 '18 at 17:49
Jonathan Leffler
569k916821032
asked Nov 24 '18 at 17:30
davidkudavidku
94
In the code forfun(), your argument toprintf()should be justcand not'c'. You probably also mean%3drather than%d3though that 'works'; it just doesn't do what you expect. Note that you should use an explicitint main(void) { … }.
– Jonathan Leffler
Nov 24 '18 at 17:45
1
The compilation problem is that you forgot the-cflags in the compiler line forbase.oandfun.o. Interestingly, the simplest fix would be to delete the two compiler command for the two object files —makeknows how to compile C files to object files. You could setCFLAGS += -Wall(orCFLAGS = -Wall) to get the (very important)-Wallflag included. Adding-Werrortoo would be good.
– Jonathan Leffler
Nov 24 '18 at 17:49
thank you very much! it works now
– davidku
Nov 24 '18 at 18:06
1
Sidenote: ANSI-C is outdated since almost 20 years. Use modern standard C, i.e. C11 resp. 17.
– too honest for this site
Nov 24 '18 at 18:45
add a comment |
After a certain attempt to write a simple program with a main and one function,
I ask for your help to find the bug. I include the 3 files that are in action:
- the main function in
base.c
- the function in
fun.c
- the
makefile
The compiler says that the function is called in a bad way in the main:
undefined reference to `fun'
base.c
#include <stdio.h>
int fun(char c);
main()
{
printf("please enter a single charn");
char c=getchar();
fun(c);
return 0;
}
fun.c
#include <stdio.h>
int fun(char c)
{
printf("%d3 is the value of your char!n", 'c');
return 0;
}
makefile
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -g -Wall -ansi fun.c -o fun.o
c makefile
edited Nov 24 '18 at 17:49
Jonathan Leffler
569k916821032
asked Nov 24 '18 at 17:30
davidkudavidku
94
After a certain attempt to write a simple program with a main and one function,
I ask for your help to find the bug. I include the 3 files that are in action:
- the main function in
base.c
- the function in
fun.c
- the
makefile
The compiler says that the function is called in a bad way in the main:
undefined reference to `fun'
base.c
#include <stdio.h>
int fun(char c);
main()
{
printf("please enter a single charn");
char c=getchar();
fun(c);
return 0;
}
fun.c
#include <stdio.h>
int fun(char c)
{
printf("%d3 is the value of your char!n", 'c');
return 0;
}
makefile
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -g -Wall -ansi fun.c -o fun.o
c makefile
c makefile
edited Nov 24 '18 at 17:49
Jonathan Leffler
569k916821032
asked Nov 24 '18 at 17:30
davidkudavidku
94
edited Nov 24 '18 at 17:49
Jonathan Leffler
569k916821032
asked Nov 24 '18 at 17:30
davidkudavidku
94
edited Nov 24 '18 at 17:49
Jonathan Leffler
569k916821032
edited Nov 24 '18 at 17:49
Jonathan Leffler
569k916821032
edited Nov 24 '18 at 17:49
Jonathan Leffler
569k916821032
569k916821032
asked Nov 24 '18 at 17:30
davidkudavidku
94
asked Nov 24 '18 at 17:30
davidkudavidku
94
asked Nov 24 '18 at 17:30
davidkudavidku
94
94
In the code forfun(), your argument toprintf()should be justcand not'c'. You probably also mean%3drather than%d3though that 'works'; it just doesn't do what you expect. Note that you should use an explicitint main(void) { … }.
– Jonathan Leffler
Nov 24 '18 at 17:45
1
The compilation problem is that you forgot the-cflags in the compiler line forbase.oandfun.o. Interestingly, the simplest fix would be to delete the two compiler command for the two object files —makeknows how to compile C files to object files. You could setCFLAGS += -Wall(orCFLAGS = -Wall) to get the (very important)-Wallflag included. Adding-Werrortoo would be good.
– Jonathan Leffler
Nov 24 '18 at 17:49
thank you very much! it works now
– davidku
Nov 24 '18 at 18:06
1
Sidenote: ANSI-C is outdated since almost 20 years. Use modern standard C, i.e. C11 resp. 17.
– too honest for this site
Nov 24 '18 at 18:45
add a comment |
In the code forfun(), your argument toprintf()should be justcand not'c'. You probably also mean%3drather than%d3though that 'works'; it just doesn't do what you expect. Note that you should use an explicitint main(void) { … }.
– Jonathan Leffler
Nov 24 '18 at 17:45
1
The compilation problem is that you forgot the-cflags in the compiler line forbase.oandfun.o. Interestingly, the simplest fix would be to delete the two compiler command for the two object files —makeknows how to compile C files to object files. You could setCFLAGS += -Wall(orCFLAGS = -Wall) to get the (very important)-Wallflag included. Adding-Werrortoo would be good.
– Jonathan Leffler
Nov 24 '18 at 17:49
thank you very much! it works now
– davidku
Nov 24 '18 at 18:06
1
Sidenote: ANSI-C is outdated since almost 20 years. Use modern standard C, i.e. C11 resp. 17.
– too honest for this site
Nov 24 '18 at 18:45
In the code for
fun(), your argument to printf() should be just c and not 'c'. You probably also mean %3d rather than %d3 though that 'works'; it just doesn't do what you expect. Note that you should use an explicit int main(void) { … }.– Jonathan Leffler
Nov 24 '18 at 17:45
In the code for
fun(), your argument to printf() should be just c and not 'c'. You probably also mean %3d rather than %d3 though that 'works'; it just doesn't do what you expect. Note that you should use an explicit int main(void) { … }.– Jonathan Leffler
Nov 24 '18 at 17:45
1
1
The compilation problem is that you forgot the
-c flags in the compiler line for base.o and fun.o. Interestingly, the simplest fix would be to delete the two compiler command for the two object files — make knows how to compile C files to object files. You could set CFLAGS += -Wall (or CFLAGS = -Wall) to get the (very important) -Wall flag included. Adding -Werror too would be good.– Jonathan Leffler
Nov 24 '18 at 17:49
The compilation problem is that you forgot the
-c flags in the compiler line for base.o and fun.o. Interestingly, the simplest fix would be to delete the two compiler command for the two object files — make knows how to compile C files to object files. You could set CFLAGS += -Wall (or CFLAGS = -Wall) to get the (very important) -Wall flag included. Adding -Werror too would be good.– Jonathan Leffler
Nov 24 '18 at 17:49
thank you very much! it works now
– davidku
Nov 24 '18 at 18:06
thank you very much! it works now
– davidku
Nov 24 '18 at 18:06
1
1
Sidenote: ANSI-C is outdated since almost 20 years. Use modern standard C, i.e. C11 resp. 17.
– too honest for this site
Nov 24 '18 at 18:45
Sidenote: ANSI-C is outdated since almost 20 years. Use modern standard C, i.e. C11 resp. 17.
– too honest for this site
Nov 24 '18 at 18:45
add a comment |
1 Answer
1
active
oldest
votes
The compilation problem is that you forgot the -c flags in the compiler line for base.o and fun.o. One obvious simple (but not very good) way to fix that is:
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -c -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -c -g -Wall -ansi fun.c -o fun.o
Interestingly, the simplest fix would be to delete the two compiler command for the two object files — make knows how to compile C files to object files. You could set CFLAGS += -Wall (or CFLAGS = -Wall) to get the (very important) -Wall flag included. Adding -Werror too would be good.
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c
fun.o: fun.c
In the code for fun(), your argument to printf() should be just c and not 'c'. You probably also mean %3d rather than %d3 though that 'works'; it just doesn't do what you expect. Note that you should use an explicit int main(void) { … }. And you should probably create a header fun.h containing:
extern int fun(char c);
and #include "fun.h" in both source files, and add fun.h after the source file name in the dependency lines in the makefile:
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c fun.h
fun.o: fun.c fun.h
In fact, you don't need to list the source files as dependencies for the object files; make will infer that dependency automatically. But you do need to specify the header file dependency.
answered Nov 24 '18 at 19:07
Jonathan LefflerJonathan Leffler
569k916821032
isn't ${CC} should be defined in Makefile?
– Sajjad Ahmed
Nov 24 '18 at 19:24
makecomes equipped with a lot of predefined macros, such asCFLAGSandCC. You can see which ones are built in withmake -p -f /dev/null, for example.
– Jonathan Leffler
Nov 24 '18 at 19:25
add a comment |
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The compilation problem is that you forgot the -c flags in the compiler line for base.o and fun.o. One obvious simple (but not very good) way to fix that is:
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -c -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -c -g -Wall -ansi fun.c -o fun.o
Interestingly, the simplest fix would be to delete the two compiler command for the two object files — make knows how to compile C files to object files. You could set CFLAGS += -Wall (or CFLAGS = -Wall) to get the (very important) -Wall flag included. Adding -Werror too would be good.
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c
fun.o: fun.c
In the code for fun(), your argument to printf() should be just c and not 'c'. You probably also mean %3d rather than %d3 though that 'works'; it just doesn't do what you expect. Note that you should use an explicit int main(void) { … }. And you should probably create a header fun.h containing:
extern int fun(char c);
and #include "fun.h" in both source files, and add fun.h after the source file name in the dependency lines in the makefile:
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c fun.h
fun.o: fun.c fun.h
In fact, you don't need to list the source files as dependencies for the object files; make will infer that dependency automatically. But you do need to specify the header file dependency.
answered Nov 24 '18 at 19:07
Jonathan LefflerJonathan Leffler
569k916821032
isn't ${CC} should be defined in Makefile?
– Sajjad Ahmed
Nov 24 '18 at 19:24
makecomes equipped with a lot of predefined macros, such asCFLAGSandCC. You can see which ones are built in withmake -p -f /dev/null, for example.
– Jonathan Leffler
Nov 24 '18 at 19:25
add a comment |
The compilation problem is that you forgot the -c flags in the compiler line for base.o and fun.o. One obvious simple (but not very good) way to fix that is:
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -c -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -c -g -Wall -ansi fun.c -o fun.o
Interestingly, the simplest fix would be to delete the two compiler command for the two object files — make knows how to compile C files to object files. You could set CFLAGS += -Wall (or CFLAGS = -Wall) to get the (very important) -Wall flag included. Adding -Werror too would be good.
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c
fun.o: fun.c
In the code for fun(), your argument to printf() should be just c and not 'c'. You probably also mean %3d rather than %d3 though that 'works'; it just doesn't do what you expect. Note that you should use an explicit int main(void) { … }. And you should probably create a header fun.h containing:
extern int fun(char c);
and #include "fun.h" in both source files, and add fun.h after the source file name in the dependency lines in the makefile:
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c fun.h
fun.o: fun.c fun.h
In fact, you don't need to list the source files as dependencies for the object files; make will infer that dependency automatically. But you do need to specify the header file dependency.
answered Nov 24 '18 at 19:07
Jonathan LefflerJonathan Leffler
569k916821032
isn't ${CC} should be defined in Makefile?
– Sajjad Ahmed
Nov 24 '18 at 19:24
makecomes equipped with a lot of predefined macros, such asCFLAGSandCC. You can see which ones are built in withmake -p -f /dev/null, for example.
– Jonathan Leffler
Nov 24 '18 at 19:25
add a comment |
The compilation problem is that you forgot the -c flags in the compiler line for base.o and fun.o. One obvious simple (but not very good) way to fix that is:
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -c -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -c -g -Wall -ansi fun.c -o fun.o
Interestingly, the simplest fix would be to delete the two compiler command for the two object files — make knows how to compile C files to object files. You could set CFLAGS += -Wall (or CFLAGS = -Wall) to get the (very important) -Wall flag included. Adding -Werror too would be good.
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c
fun.o: fun.c
In the code for fun(), your argument to printf() should be just c and not 'c'. You probably also mean %3d rather than %d3 though that 'works'; it just doesn't do what you expect. Note that you should use an explicit int main(void) { … }. And you should probably create a header fun.h containing:
extern int fun(char c);
and #include "fun.h" in both source files, and add fun.h after the source file name in the dependency lines in the makefile:
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c fun.h
fun.o: fun.c fun.h
In fact, you don't need to list the source files as dependencies for the object files; make will infer that dependency automatically. But you do need to specify the header file dependency.
answered Nov 24 '18 at 19:07
Jonathan LefflerJonathan Leffler
569k916821032
The compilation problem is that you forgot the -c flags in the compiler line for base.o and fun.o. One obvious simple (but not very good) way to fix that is:
charprint: base.o fun.o
gcc -g -Wall -ansi base.o fun.o -o charprint
base.o: base.c
gcc -c -g -Wall -ansi base.c -o base.o
fun.o: fun.c
gcc -c -g -Wall -ansi fun.c -o fun.o
Interestingly, the simplest fix would be to delete the two compiler command for the two object files — make knows how to compile C files to object files. You could set CFLAGS += -Wall (or CFLAGS = -Wall) to get the (very important) -Wall flag included. Adding -Werror too would be good.
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c
fun.o: fun.c
In the code for fun(), your argument to printf() should be just c and not 'c'. You probably also mean %3d rather than %d3 though that 'works'; it just doesn't do what you expect. Note that you should use an explicit int main(void) { … }. And you should probably create a header fun.h containing:
extern int fun(char c);
and #include "fun.h" in both source files, and add fun.h after the source file name in the dependency lines in the makefile:
CFLAGS += -Wall -Werror -g -std=c11
charprint: base.o fun.o
${CC} ${CFLAGS} base.o fun.o -o $@
base.o: base.c fun.h
fun.o: fun.c fun.h
In fact, you don't need to list the source files as dependencies for the object files; make will infer that dependency automatically. But you do need to specify the header file dependency.
answered Nov 24 '18 at 19:07
Jonathan LefflerJonathan Leffler
569k916821032
answered Nov 24 '18 at 19:07
Jonathan LefflerJonathan Leffler
569k916821032
answered Nov 24 '18 at 19:07
Jonathan LefflerJonathan Leffler
569k916821032
answered Nov 24 '18 at 19:07
Jonathan LefflerJonathan Leffler
569k916821032
569k916821032
isn't ${CC} should be defined in Makefile?
– Sajjad Ahmed
Nov 24 '18 at 19:24
makecomes equipped with a lot of predefined macros, such asCFLAGSandCC. You can see which ones are built in withmake -p -f /dev/null, for example.
– Jonathan Leffler
Nov 24 '18 at 19:25
add a comment |
isn't ${CC} should be defined in Makefile?
– Sajjad Ahmed
Nov 24 '18 at 19:24
makecomes equipped with a lot of predefined macros, such asCFLAGSandCC. You can see which ones are built in withmake -p -f /dev/null, for example.
– Jonathan Leffler
Nov 24 '18 at 19:25
isn't ${CC} should be defined in Makefile?
– Sajjad Ahmed
Nov 24 '18 at 19:24
isn't ${CC} should be defined in Makefile?
– Sajjad Ahmed
Nov 24 '18 at 19:24
make comes equipped with a lot of predefined macros, such as CFLAGS and CC. You can see which ones are built in with make -p -f /dev/null, for example.– Jonathan Leffler
Nov 24 '18 at 19:25
make comes equipped with a lot of predefined macros, such as CFLAGS and CC. You can see which ones are built in with make -p -f /dev/null, for example.– Jonathan Leffler
Nov 24 '18 at 19:25
add a comment |
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In the code for
fun(), your argument toprintf()should be justcand not'c'. You probably also mean%3drather than%d3though that 'works'; it just doesn't do what you expect. Note that you should use an explicitint main(void) { … }.– Jonathan Leffler
Nov 24 '18 at 17:45
1
The compilation problem is that you forgot the
-cflags in the compiler line forbase.oandfun.o. Interestingly, the simplest fix would be to delete the two compiler command for the two object files —makeknows how to compile C files to object files. You could setCFLAGS += -Wall(orCFLAGS = -Wall) to get the (very important)-Wallflag included. Adding-Werrortoo would be good.– Jonathan Leffler
Nov 24 '18 at 17:49
thank you very much! it works now
– davidku
Nov 24 '18 at 18:06
1
Sidenote: ANSI-C is outdated since almost 20 years. Use modern standard C, i.e. C11 resp. 17.
– too honest for this site
Nov 24 '18 at 18:45