I want to build this process on an embedded Linux without installing sqlite3 or sqlite3-dev (I already tried to install them and it worked out).
I've 4 files in the directory : main.cpp sqlite3.c sqlite3.h example.db
I included the sqlite3.h in the main.cpp this way:
extern "C"{
#include "sqlite3.h"
}
Then I typed those commands :
gcc -c sqlite3.c -o sqlite3.o
g++ -c main.cpp -o main.o
and it was already so far, then I wrote this
g++ -o main.out main.o -L.
but I'm getting those errors
main.o: In function `main':
main.cpp:(.text+0xf6): undefined reference to `sqlite3_open'
main.cpp:(.text+0x16d): undefined reference to `sqlite3_exec'
main.cpp:(.text+0x1c6): undefined reference to `sqlite3_exec'
main.cpp:(.text+0x1f7): undefined reference to `sqlite3_free'
main.cpp:(.text+0x25c): undefined reference to `sqlite3_exec'
main.cpp:(.text+0x299): undefined reference to `sqlite3_exec'
main.cpp:(.text+0x2ca): undefined reference to `sqlite3_free'
main.cpp:(.text+0x32f): undefined reference to `sqlite3_exec'
main.cpp:(.text+0x33b): undefined reference to `sqlite3_close'
collect2: error: ld returned 1 exit status
How to statically link those files?
You're not actually linking with the SQLite object file sqlite3.o.
The linker doesn't know about files or libraries that aren't specified explicitly, so you need to do e.g.
g++ -o main.out main.o sqlite3.o
Considering the other error you get, you need to build with the -pthread option, both when compiling and when linking.
And the -L option is to add a path that the library searches for libraries you name with the -l (lower-case L) option. The linker will not automatically search for any libraries or object files. You really need to specify them explicitly when linking.
To summarize, build like this:
g++ -Wall -pthread main.cpp -c
gcc -Wall -pthread sqlite3.c -c
g++ -pthread -o main.out main.o sqlite3.o -ldl
Note that we now also link with the dl library, as specified in the documentation linked to by Shawn.