Trouble Writing My First Makefile - c

Question

So here is my Makefile:
# My First Makefile
HEADERS = stdio.h
all: main.o input.o output.o
cc -o all main.o input.o output.o
main.o: main.c $(HEADERS)
cc -c main.c -o main.o
input.o: input.c $(HEADERS)
cc -c input.c -o input.o
output.o: output.c $(HEADERS)
cc -c output.c -o output.o
clean:
-rm -f *.o
-rm -f all
And below is input.c:
#ifndef __STDIO_H__
#define __STDIO_H__
#include <stdio.h>
void getChar()
{
getchar();
}
#endif
Below is output.c:
#ifndef __STDIO_H__
#define __STDIO_H__
#include <stdio.h>
void putChar(char c)
{
putchar(c);
}
#endif
Below is main.c:
#ifndef __STDIO_H__
#define __STDIO_H__
#include <stdio.h>
int main()
{
char c;
while ((c = etChar()) != '\n')
{
putChar(c);
}
}
#endif
Yet whenever I press "make" command in Terminal,
I get:
make: *** No rule to make target `stdio.h', needed by `main.o'. Stop.
cc refers to clang
What is it that I am doing wrong here?
I was trying to get used to $(ARGS) by using $(HEADERS)
but it seems that the clang compiler does not accept this.
Do you think I should use gcc instead?

Answer 1

It is unnecessary to write stdio.h in your Makefile. GCC will automatically search it in DEFAULT PATH (/usr/include, ....). Write header files as targes in Makefile only if you use your own header files.
# Makefile
# define CC
CC := gcc
# define final targets
TARGETS := main
# just trigger $(TARGETS)
all: $(TARGETS)
# build main from main.o, input.o, output.o
main: main.o input.o output.o
$(CC) -o $# $^
# build main.o/input.o/output.c from main.c/input.c/output.c
%.o: %.c
$(CC) -c -o $# $<
# trigger $(TARGETS), then run ./main
run: $(TARGETS)
./main
clean:
-rm $(TARGETS)
-rm *.o
# define targets which are not bound to file
.PHONY: all clean run

Answer 2

In your case:
"make" will look for stdio.h in the current directory, and is complaining that the header is not found.
Just to fix this, you should mention the full path where stdio.h is located, for example:
HEADERS = /usr/include/stdio.h
Ideally, if you want to check for the presence of standard headers like stdio.h, you should use tools like automake and autoconf, which generate the Makefile automatically. Here's a link which points to the autoconf documentation:
https://www.gnu.org/software/automake/manual/html_node/Autotools-Introduction.html