Why do I get "undefined reference to ..." errors when I included the library?

Question

1.00/5 (1 vote)

See more:

Please look at this github that explains how to use ChatScript as a library inside a C/C++ program(only see Embedding step1 and 2): [^]

As the tutorial says, I must do 2 calls.
1. InitSystem() function call to initialize the library.
2-performChat() function to pass a string to library and get the output string as the answer.

What I have tried:

So I wrote this simple C++ code:

#include <iostream>
#include "common.h"
#include "mainSystem.h"

using namespace std;


int main(int argc, char * argv[])
{
char* input="hi";
char* output;
char * userID="one";

InitSystem (0, NULL);
void InitStandalone();

PerformChat("one","Harry",input,NULL,output);

cout<<output;

    return 0;
}

And I know both the mentioned functions are inside of mainSystem.cpp, so I did include that file to my program.(this is mainSystem.h : https://github.com/bwilcox-1234/ChatScript/blob/master/SRC/mainSystem.h and this is mainSystem.cpp https://github.com/bwilcox-1234/ChatScript/blob/master/SRC/mainSystem.cpp)

Everything looks OK but when I try to compile my code by

C++

g++ -o mayprogram main.o

it says:

main.o: In function `main':
main.cpp:(.text+0x44): undefined reference to `InitSystem(int, char**, char*, char*, char*, USERFILESYSTEM*, void (*)(char*), void (*)(char*))'
main.cpp:(.text+0x6a): undefined reference to `PerformChat(char*, char*, char*, char*, char*)'
collect2: error: ld returned 1 exit status

It's very strange for me!!! Why do I get this error message when I included the mainSystem.h above my code?

***about main.o I must say I built it by running

C++

make standalone

command before, with my

C++

main.cpp

successfully!

This is the make file:

.PHONY = clean binary server debugserver standalone pgserver debugpgserver mysqlserver debugmysqlserver mongoserver debugmongoserver foreignserver mongotreetaggerserver 

# Removed the 'all' target.  It does not  make sense since each build target requires a different set of defines.
# So we need to clean before building each target in order compile in the right stuff.  
#
# E.g. to build pg and mysql:
#
# 1. make clean pgserver
# 2. make clean mysqlserver

# Note: to build mysql targets on Ubuntu:
# sudo apt-get install libmysqlclient-dev

# store executable names in make variables so that cleanall target works
executable.server=../BINARIES/ChatScript
server: DEFINES+= -DLOCKUSERFILE=1  -DEVSERVER=1 -DEVSERVER_FORK=1  -DDISCARDPOSTGRES=1 -DDISCARDMONGO=1 -DDISCARDMYSQL=1 
server: PGLOAD= -pthread
server: INCLUDEDIRS=-Ievserver
server: binary
server: EXECUTABLE=$(executable.server)
server: CFLAGS=-c  -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing 

executable.debugserver=../BINARIES/ChatScriptDebug
debugserver: DEFINES+= -DLOCKUSERFILE=1 -DDISCARDPOSTGRES=1 -DDISCARDMONGO=1 -DDISCARDMYSQL=1  -DDEBUG -DEVSERVER=1 -DEVSERVER_FORK=1 
debugserver: PGLOAD= -pthread
debugserver: INCLUDEDIRS=-Ievserver
debugserver: binary
debugserver: EXECUTABLE=$(executable.debugserver)
debugserver: CFLAGS=-c -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing -g

executable.standalone=../BINARIES/CS_LINUX
standalone: DEFINES+=  -DDISCARDSERVER=1 -DDISCARDPOSTGRES=1 -DDISCARDMONGO=1 -DDISCARDMYSQL=1 -DEVSERVER=1 -DEVSERVER_FORK=1
standalone: PGLOAD= -pthread
standalone: INCLUDEDIRS=-Ievserver
standalone: binary
standalone: EXECUTABLE=$(executable.standalone)
standalone: CFLAGS=-c -std=c++11  -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing 

executable.pgserver=../BINARIES/ChatScriptpg
pgserver: DEFINES+= -DLOCKUSERFILE=1 -DEVSERVER=1 -DEVSERVER_FORK=1 -DDISCARDMONGO=1 -DDISCARDMYSQL=1
pgserver: PGLOAD= -lpq -pthread
pgserver: binary
pgserver: EXECUTABLE=$(executable.pgserver)
pgserver: INCLUDEDIRS=-Ievserver -Ipostgres
pgserver: CFLAGS=-c -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing 

executable.debugpgserver=../BINARIES/ChatScriptpgDebug
debugpgserver: DEFINES+= -DLOCKUSERFILE=1  -DDEBUG -DEVSERVER=1 -DEVSERVER_FORK=1  -DDISCARDMONGO=1 -DDISCARDMYSQL=1
debugpgserver: PGLOAD= -lpq -pthread
debugpgserver: INCLUDEDIRS=-Ievserver -Ipostgres 
debugpgserver: binary
debugpgserver: EXECUTABLE=$(executable.debugpgserver)
debugpgserver: CFLAGS=-c -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing -g

executable.mysqlserver=../BINARIES/ChatScriptMysql
mysqlserver: DEFINES+= -DLOCKUSERFILE=1 -DEVSERVER=1 -DEVSERVER_FORK=1 -DDISCARDPOSTGRES=1 -DDISCARDMONGO=1
mysqlserver: PGLOAD= -lmysqlclient -pthread
mysqlserver: binary
mysqlserver: EXECUTABLE=$(executable.mysqlserver)
mysqlserver: INCLUDEDIRS=-Ievserver 
mysqlserver: CFLAGS=-c -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing 

executable.debugmysqlserver=../BINARIES/ChatScriptMysqlDebug
debugmysqlserver: DEFINES+= -DLOCKUSERFILE=1  -DDEBUG -DEVSERVER=1 -DEVSERVER_FORK=1 -DDISCARDPOSTGRES=1 -DDISCARDMONGO=1  
debugmysqlserver: PGLOAD= -lmysqlclient -pthread 
debugmysqlserver: INCLUDEDIRS=-Ievserver
debugmysqlserver: binary
debugmysqlserver: EXECUTABLE=$(executable.debugmysqlserver)
debugmysqlserver: CFLAGS=-c -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing -g

executable.mongoserver=../BINARIES/ChatScriptMongo
mongoserver: DEFINES+= -DLOCKUSERFILE=1 -DEVSERVER=1 -DEVSERVER_FORK=1 -DDISCARDPOSTGRES=1 -DDISCARDMYSQL=1
mongoserver: PGLOAD= -pthread
mongoserver: binary
mongoserver: EXECUTABLE=$(executable.mongoserver)
mongoserver: INCLUDEDIRS=-Iinclude -I/usr/local/include/libbson-1.0 -I/usr/local/include/libmongoc-1.0
mongoserver: CFLAGS=-c -std=c++11  -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing -g

executable.debugmongoserver=../BINARIES/ChatScriptMongoDebug
debugmongoserver: DEFINES+= -DLOCKUSERFILE=1  -DDEBUG -DEVSERVER=1 -DEVSERVER_FORK=1  -DDISCARDPOSTGRES=1  -DDISCARDMYSQL=1
debugmongoserver: PGLOAD= -lpq -pthread
debugmongoserver: binary
debugmongoserver: INCLUDEDIRS=-Iinclude -I/usr/local/include/libbson-1.0 -I/usr/local/include/libmongoc-1.0
debugmongoserver: EXECUTABLE=$(executable.debugmongoserver)
debugmongoserver: CFLAGS=-c -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing -g

executable.foreignserver=../BINARIES/ChatScriptForeign
foreignserver: DEFINES+= -DLOCKUSERFILE=1  -DEVSERVER=1 -DEVSERVER_FORK=1  -DDISCARDPOSTGRES=1 -DDISCARDMONGO=1 -DDISCARDMYSQL=1 -DTREETAGGER=1
foreignserver: PGLOAD= -pthread -L../treetagger -L../BINARIES -ltreetagger
foreignserver: INCLUDEDIRS=-Ievserver
foreignserver: binary
foreignserver: EXECUTABLE=$(executable.foreignserver)
foreignserver: CFLAGS=-c -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing 

executable.mongotreetaggerserver=../BINARIES/ChatScriptMongoForeign
mongotreetaggerserver: DEFINES+= -DLOCKUSERFILE=1  -DEVSERVER=1 -DEVSERVER_FORK=1  -DDISCARDPOSTGRES=1  -DDISCARDMYSQL=1 -DTREETAGGER=1
mongotreetaggerserver: PGLOAD= -pthread -L../treetagger -L../BINARIES -ltreetagger
mongotreetaggerserver: INCLUDEDIRS=-Iinclude -I/usr/local/include/libbson-1.0 -I/usr/local/include/libmongoc-1.0
mongotreetaggerserver: binary
mongotreetaggerserver: EXECUTABLE=$(executable.mongotreetaggerserver)
mongotreetaggerserver: CFLAGS=-c -std=c++11 -Wall  -funsigned-char  -Wno-write-strings -Wno-char-subscripts -Wno-strict-aliasing 

UNAME := $(shell uname)

CC=g++

ifeq ($(UNAME), Linux)
$(info ************ LINUX VERSION ************)
LDFLAGS= -L/usr/lib64 -lrt -lcurl  --verbose $(PGLOAD)
mongoserver: LDFLAGS+= -lcrypt -lsasl2 -L/usr/local/lib -lmongoc-1.0 -lbson-1.0 
debugmongoserver: LDFLAGS+= -lcrypt -lsasl2 -L/usr/local/lib -lmongoc-1.0 -lbson-1.0 
mongotreetaggerserver: LDFLAGS+= -lcrypt -lsasl2 -L/usr/local/lib -lmongoc-1.0 -lbson-1.0 
endif

ifeq ($(UNAME), Darwin)
OSXRELEASE := $(shell defaults read loginwindow SystemVersionStampAsString)
$(info ************ MAC VERSION $OSXRELEASE detected ************)
LDFLAGS=-mmacosx-version-min=$(OSXRELEASE) -lcurl $(PGLOAD)  
CFLAGS=-mmacosx-version-min=$(OSXRELEASE) -c  -Wall  -funsigned-char -Wno-write-strings -Wno-char-subscripts 
endif

ifeq ($(UNAME), FreeBSD)
$(info ************ FREEBSD VERSION ************)
DEFINES+= -DFREEBSD=1
INCLUDEDIRS+= -I/usr/local/include
LDFLAGS= -L/usr/local/lib -lrt -lcurl -lev  --verbose $(PGLOAD)
mongoserver: LDFLAGS+= -lgcrypt -lsasl2 -lmongoc-1.0 -lbson-1.0 
debugmongoserver: LDFLAGS+= -lgcrypt -lsasl2 -lmongoc-1.0 -lbson-1.0 
mongotreetaggerserver: LDFLAGS+= -lgcrypt -lsasl2 -lmongoc-1.0 -lbson-1.0 
endif

SOURCES=main.cpp constructCode.cpp duktape/duktape.cpp evserver.cpp csocket.cpp cs_ev.c dictionarySystem.cpp englishTagger.cpp factSystem.cpp json.cpp functionExecute.cpp english.cpp infer.cpp javascript.cpp jsmn.cpp markSystem.cpp mysql.cpp mongodb.cpp os.cpp outputSystem.cpp patternSystem.cpp postgres.cpp privatesrc.cpp scriptCompile.cpp spellcheck.cpp secure.cpp systemVariables.cpp tagger.cpp testing.cpp textUtilities.cpp tokenSystem.cpp topicSystem.cpp userCache.cpp userSystem.cpp variableSystem.cpp mainSystem.cpp 
OBJECTS=$(SOURCES:.cpp=.o)

default: server

clean:
	-rm -f *.o

cleanall: clean
	-rm -f $(executable.server)
	-rm -f $(executable.debugserver)
	-rm -f $(executable.standalone)
	-rm -f $(executable.pgserver)
	-rm -f $(executable.debugpgserver)
	-rm -f $(executable.mysqlserver)
	-rm -f $(executable.debugmysqlserver)
	-rm -f $(executable.mongoserver)
	-rm -f $(executable.debugmongoserver)
	-rm -f $(executable.foreignserver)
	-rm -f $(executable.mongotreetaggerserver)

binary: $(OBJECTS)
	$(CC) $(OBJECTS) $(LDFLAGS) $(DEFINES) $(INCLUDEDIRS) -o $(EXECUTABLE)

.cpp.o:
	$(CC) $(CFLAGS) $(DEFINES) $(INCLUDEDIRS) $< -o $@

EDIT: when I try this command:

g++ -std=c++11 -o myprogram main.cpp constructCode.cpp duktape/duktape.cpp evserver.cpp csocket.cpp cs_ev.c dictionarySystem.cpp englishTagger.cpp factSystem.cpp json.cpp functionExecute.cpp english.cpp infer.cpp javascript.cpp jsmn.cpp markSystem.cpp mysql.cpp mongodb.cpp os.cpp outputSystem.cpp patternSystem.cpp postgres.cpp privatesrc.cpp scriptCompile.cpp spellcheck.cpp secure.cpp systemVariables.cpp tagger.cpp testing.cpp textUtilities.cpp tokenSystem.cpp topicSystem.cpp userCache.cpp userSystem.cpp variableSystem.cpp mainSystem.cpp

It gives me this result:

                                                    ^
/tmp/ccU6n5Cp.o: In function `CurlShutdown()':
json.cpp:(.text+0x1863): undefined reference to `curl_global_cleanup'
/tmp/ccU6n5Cp.o: In function `InitCurl()':
json.cpp:(.text+0x1882): undefined reference to `curl_global_init'
/tmp/ccU6n5Cp.o: In function `UrlEncodePiece(char*)':
json.cpp:(.text+0x18b5): undefined reference to `curl_easy_init'
json.cpp:(.text+0x1902): undefined reference to `curl_easy_escape'
json.cpp:(.text+0x193a): undefined reference to `curl_free'
json.cpp:(.text+0x1946): undefined reference to `curl_easy_cleanup'
/tmp/ccU6n5Cp.o: In function `encodeSegment(char**, char*, char*, void*)':
json.cpp:(.text+0x1a05): undefined reference to `curl_easy_escape'
json.cpp:(.text+0x1a28): undefined reference to `curl_free'
/tmp/ccU6n5Cp.o: In function `JSONOpenCode(char*)':
json.cpp:(.text+0x236d): undefined reference to `curl_easy_init'
json.cpp:(.text+0x255e): undefined reference to `curl_easy_setopt'
json.cpp:(.text+0x257e): undefined reference to `curl_easy_setopt'
json.cpp:(.text+0x25a5): undefined reference to `curl_easy_setopt'
json.cpp:(.text+0x25c5): undefined reference to `curl_easy_setopt'
json.cpp:(.text+0x25ec): undefined reference to `curl_easy_setopt'
/tmp/ccU6n5Cp.o:json.cpp:(.text+0x260c): more undefined references to `curl_easy_setopt' follow
/tmp/ccU6n5Cp.o: In function `JSONOpenCode(char*)':
json.cpp:(.text+0x2620): undefined reference to `curl_slist_append'
json.cpp:(.text+0x2991): undefined reference to `curl_slist_append'
json.cpp:(.text+0x2bc2): undefined reference to `curl_easy_setopt'
json.cpp:(.text+0x2c28): undefined reference to `curl_easy_setopt'
json.cpp:(.text+0x2c8a): undefined reference to `curl_easy_setopt'
json.cpp:(.text+0x2cf7): undefined reference to `curl_easy_setopt'
json.cpp:(.text+0x2d26): undefined reference to `curl_easy_setopt'
/tmp/ccU6n5Cp.o:json.cpp:(.text+0x2d53): more undefined references to `curl_easy_setopt' follow
/tmp/ccU6n5Cp.o: In function `JSONOpenCode(char*)':
json.cpp:(.text+0x2ea7): undefined reference to `curl_easy_perform'
json.cpp:(.text+0x2ecb): undefined reference to `curl_easy_getinfo'
json.cpp:(.text+0x31cf): undefined reference to `curl_slist_free_all'
json.cpp:(.text+0x31de): undefined reference to `curl_easy_cleanup'
/tmp/ccaIe2WK.o: In function `mysqlUserRead(void*, unsigned long, unsigned long, _IO_FILE*)':
mysql.cpp:(.text+0xe5): undefined reference to `mysql_stmt_init'
mysql.cpp:(.text+0x10c): undefined reference to `mysql_error'
mysql.cpp:(.text+0x14e): undefined reference to `mysql_stmt_prepare'
mysql.cpp:(.text+0x16b): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x1fe): undefined reference to `mysql_stmt_bind_param'
mysql.cpp:(.text+0x21b): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x241): undefined reference to `mysql_stmt_execute'
mysql.cpp:(.text+0x25e): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x284): undefined reference to `mysql_stmt_store_result'
mysql.cpp:(.text+0x2a1): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x2c7): undefined reference to `mysql_stmt_num_rows'
mysql.cpp:(.text+0x360): undefined reference to `mysql_stmt_bind_result'
mysql.cpp:(.text+0x37d): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x3a3): undefined reference to `mysql_stmt_fetch'
mysql.cpp:(.text+0x3ea): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x420): undefined reference to `mysql_stmt_error'
/tmp/ccaIe2WK.o: In function `mysqlUserWrite(void const*, unsigned long, unsigned long, _IO_FILE*)':
mysql.cpp:(.text+0x56f): undefined reference to `mysql_stmt_init'
mysql.cpp:(.text+0x596): undefined reference to `mysql_error'
mysql.cpp:(.text+0x5d8): undefined reference to `mysql_stmt_prepare'
mysql.cpp:(.text+0x5f5): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x6cb): undefined reference to `mysql_stmt_bind_param'
mysql.cpp:(.text+0x6e8): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x719): undefined reference to `mysql_stmt_execute'
mysql.cpp:(.text+0x731): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x747): undefined reference to `mysql_stmt_errno'
mysql.cpp:(.text+0x784): undefined reference to `mysql_stmt_affected_rows'
mysql.cpp:(.text+0x7c0): undefined reference to `mysql_stmt_init'
mysql.cpp:(.text+0x7e7): undefined reference to `mysql_error'
mysql.cpp:(.text+0x829): undefined reference to `mysql_stmt_prepare'
mysql.cpp:(.text+0x846): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x91c): undefined reference to `mysql_stmt_bind_param'
mysql.cpp:(.text+0x939): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x95f): undefined reference to `mysql_stmt_execute'
mysql.cpp:(.text+0x97c): undefined reference to `mysql_stmt_error'
mysql.cpp:(.text+0x9a2): undefined reference to `mysql_stmt_affected_rows'
mysql.cpp:(.text+0x9c7): undefined reference to `mysql_stmt_error'
/tmp/ccaIe2WK.o: In function `MySQLUserFilesCode()':
mysql.cpp:(.text+0xa09): undefined reference to `mysql_init'
mysql.cpp:(.text+0xa66): undefined reference to `mysql_real_connect'
mysql.cpp:(.text+0xa91): undefined reference to `mysql_error'
/tmp/ccaIe2WK.o: In function `MySQLInitCode(char*)':
mysql.cpp:(.text+0xb45): undefined reference to `mysql_init'
mysql.cpp:(.text+0xb72): undefined reference to `mysql_real_connect'
mysql.cpp:(.text+0xb8c): undefined reference to `mysql_error'
mysql.cpp:(.text+0xbc3): undefined reference to `mysql_query'
mysql.cpp:(.text+0xbd8): undefined reference to `mysql_error'
mysql.cpp:(.text+0xc0a): undefined reference to `mysql_use_result'
mysql.cpp:(.text+0xc24): undefined reference to `mysql_fetch_row'
mysql.cpp:(.text+0xc5b): undefined reference to `mysql_free_result'
mysql.cpp:(.text+0xc67): undefined reference to `mysql_close'
collect2: error: ld returned 1 exit status

Posted 25-Oct-17 7:28am

Member 13376650

Updated 27-Oct-17 1:15am

v6

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Richard MacCutchan · Answer 1 · 2017-10-25T07:43:00

Solution 1

You need to include the library(s) that contain the code for those functions, which are merely defined in the header files. See the LDFLAGS entries in your Makefile for the required options.

You also have the line

C++

void InitStandalone();

in your main function. Are you sure that is supposed to be there?

Posted 25-Oct-17 7:43am

Richard MacCutchan

Comments

Member 13376650 25-Oct-17 14:33pm

About the InitStandalone() function, I saw it in another tutorial that it said:

To call these routines, your code will need a predeclaration of these
routines. Just copy the routine declarations from ChatScript and put
at the start of your file, e.g.,

unsigned int InitSystem(int argc, char * argv[],char* unchangedPath,char* readonlyPath, char* writablePath);
void InitStandalone();
void PerformChat(char* user, char* usee, char* incoming,char* ip,char* output);

Also it's inside the mainSystem.h too

Member 13376650 25-Oct-17 14:35pm

About another header files that should be included, may you explain more how can I find them? I am newbie in Linux and couldn't find them !

Richard MacCutchan 26-Oct-17 4:11am

This has nothing to do with Linux, it is purely a compile and link issue with the C language. If you do not know how to link your object modules and libraries you need to take a look at the gcc/g++ documentation.

Member 13376650 27-Oct-17 5:40am

I asked the author and he said "only common.h" is sufficient to add above my main! And I saw inside common.h, "mainSystem.h" is included. and inside "mainSystem.h" there is "evserver.h" . and I have all of this header file beside my main!

But I don't know why I get damn "undefined reference ..." errors!

Richard MacCutchan 27-Oct-17 6:20am

And I have explained twice that this is an issue with missing libraries, not header files. If you do not understand how linking of object modules is used to create executable programs, then you need to study the documentation for the GCC compilation system, and the ld linker.

Member 13376650 27-Oct-17 7:08am

But what does the makefile do? Why it ran successfully?

Richard MacCutchan 27-Oct-17 7:14am

Look at the item titled LDFLAGS, that is where the required libraries are listed. Type "man ld" and "man make" in a Linux terminal window to learn about these two commands.

Member 13376650 27-Oct-17 7:16am

Please read my edit section I added to my question

Richard MacCutchan 27-Oct-17 7:51am

How many times do you want me to repeat myself? You cannot create executable programs without linking the required system and language libraries.

Member 13376650 31-Oct-17 1:35am

I have a question! Why when I use mainSystem.cpp file and it's main function(at the end of the file) I can compile it, but when I use a separate main.cpp file with exactly those heder files there are in mainSystem.cpp file, they don't work?

Richard MacCutchan 31-Oct-17 4:51am

Probably because you refuse to read my answers.

Member 13376650 31-Oct-17 5:19am

I had this problem in compiling a cpp program written to use espeak library too, and a user said use "-l espeak-ng" after "g++ testSpeak -o speak" and it worked! Should I do something like this for this question?

Richard MacCutchan 31-Oct-17 6:03am

Exactly, as I told you more than once already.

Member 13376650 31-Oct-17 7:19am

I am new to Linux and sorry if I got it too late! But I have new question, how can I find what should I type after "-l " ?
You said I must looking for the options after LDFLAGS inside makefile, but as you can see there are three LDFLAGS with different options!

Richard MacCutchan 31-Oct-17 7:43am

I have already explained that this is not a Linux issue. This is about compiling source code into object modules, and then linking those objects into an executable program. The documentation for any libraries that you use should tell you the library name that you need to include in your build (using the -l and -L flags). If you have a Makefile then it will include the information, as here, in a LDFLAGS tag. The ones you need to use for this build are the ones listed as follows, identified by the line that tests to see if you are building on Linux:


ifeq ($(UNAME), Linux)
$(info ************ LINUX VERSION ************)
LDFLAGS= -L/usr/lib64 -lrt -lcurl  --verbose $(PGLOAD)
mongoserver: LDFLAGS+= -lcrypt -lsasl2 -L/usr/local/lib -lmongoc-1.0 -lbson-1.0 
debugmongoserver: LDFLAGS+= -lcrypt -lsasl2 -L/usr/local/lib -lmongoc-1.0 -lbson-1.0 
mongotreetaggerserver: LDFLAGS+= -lcrypt -lsasl2 -L/usr/local/lib -lmongoc-1.0 -lbson-1.0 
endif

But blindly following something like this is not a good way to learn. You should study the documentation for gcc/g++. You should also use the Linux man pages to learn about ld and make.

Member 13376650 1-Nov-17 8:41am

I tried this:

g++ -std=c++11 main.cpp constructCode.cpp csocket.cpp dictionarySystem.cpp english.cpp evserver.cpp factSystem.cpp functionExecute.cpp infer.cpp jsmn.cpp json.cpp markSystem.cpp mongodb.cpp mysql.cpp os.cpp outputSystem.cpp patternSystem.cpp postgres.cpp privatesrc.cpp scriptCompile.cpp spellcheck.cpp systemVariables.cpp tagger.cpp testing.cpp textUtilities.cpp tokenSystem.cpp topicSystem.cpp userCache.cpp userSystem.cpp variableSystem.cpp -o myprogram -lrt -lcurl --verbose

But got many "undefined reference to ..." errors again :(

Richard MacCutchan 1-Nov-17 9:13am

No wonder, you did not include most of the libraries.

Member 13376650 1-Nov-17 11:18am

May you say what command I should use to compile and link it successfully?
And introduce a simple tutorial about this?

Richard MacCutchan 1-Nov-17 11:29am

I have told you already, more than once: Study the documentation.

Member 13376650 1-Nov-17 12:29pm

please give me more specified guide! What document? which part?