Makefile include erro

Question

I am new to makefile I have this error while compiling.

all: main
main.o:ssh-functions.o mysql_connector.o
    g++ -c main.c ssh-functions.o mysql_connector.o -I libuv/include -L libuv/ -luv -lrt -lpthread
ssh-functions.o:ssh-functions.cpp 
    g++ -c  ssh-functions.cpp -lssl -lcrypto 
mysql_connector.o: mysql_connector.c
    g++ -I/usr/include/mysql/ -c mysql_connector.c -L/usr/include/mysql/ -lmysqlclient 

clean:
    rm -rf *.o

output:

g++ -c  ssh-functions.cpp -lssl -lcrypto
g++ -I/usr/include/mysql/ -c mysql_connector.c -L/usr/include/mysql/ -lmysqlclient
g++ -c main.c ssh-functions.o mysql_connector.o -I libuv/include -L libuv/ -luv -lrt -lpthread
In file included from main.c:4:0:
mysql_connector.c:4:19: fatal error: mysql.h: No such file or directory
compilation terminated.
make: *** [main.o] Error 1

Answer 1

You need to add the -I/usr/include/mysql on each compiler invocation that will compile source code that contains #include <mysql.h> or equivalent.

You're missing that on the line that compiles main.c .

Tip 1: move the -I (include search paths) to before the source code files you're compiling, and the -L (library search paths) and -l (libraries) parts to after the code files. -I is for the preprocessor, that runs first . -L and -l are for the linker, that runs last .

Tip 2: do not use -lpthread unless you know exactly what you're doing. Use -pthread instead. And if you need it for one compile, your most likely need it for all the compiles in the same project. (And put that in front of everything, that affects the complete compilation, pre-processor and linker.)

Answer 2

Try s.th. like this (eventually replace main with main.exe this depends on your target OS environment):

MY_INCLPATHS=-I /usr/include/mysql -I libuv/include
MY_LIBPATHS=-L /usr/include/mysql -L libuv/
MY_LIBS=-lmysqlclient -lssl -lcrypto -luv -lrt -lpthread

all: main
main: main.o ssh-functions.o mysql_connector.o   
    g++ ${MY_LIBPATHS} main.o ssh-functions.o mysql_connector.o ${MY_LIBS} -o main
main.o: main.c
    g++  ${MY_INCLPATHS} -c main.c
ssh-functions.o: ssh-functions.cpp 
    g++  ${MY_INCLPATHS} -c ssh-functions.cpp
mysql_connector.o: mysql_connector.c
     g++ ${MY_INCLPATHS} -c mysql_connector.c  

clean:
    rm -rf main *.o