Undefined reference in c... What am I doing wrong? - c++

Question

I have the following code... which is throwing a main.cpp:18: undefined reference to phrase_init() Coming from C# experience C is a bit annoying especially when trying to figure out where the problem is :( Any idea or pointer will be greatly appreciated!
phrase.h:
#ifndef PHRASE_H
#define PHRASE_H
typedef struct
{
char* Word1;
char* Word2;
} Phrase;
Phrase* phrase_init(void);
#endif
Phrase.c :
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include "phrase.h"
Phrase* phrase_init()
{
Phrase* phrase = (Phrase *)malloc(sizeof(Phrase));
phrase->Word1 = (char *)malloc(sizeof(char));
phrase->Word2 = (char *)malloc(sizeof(char));
return phrase;
}
main.c
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <cctype>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include "phrase.h"
int main(int argc, char** argv) {
char* word1 = "Testing";
char* word2 = "Word2";
Phrase* test = phrase_init();
strcpy(test->Word1, word1);
strcpy(test->Word2, word2);
printf("Word 1: %s", test->Word1);
printf("Word 2: %s", test->Word2);
scanf("%s", word1);
}
Makefile:
#
# There exist several targets which are by default empty and which can be
# used for execution of your targets. These targets are usually executed
# before and after some main targets. They are:
#
# .build-pre: called before 'build' target
# .build-post: called after 'build' target
# .clean-pre: called before 'clean' target
# .clean-post: called after 'clean' target
# .clobber-pre: called before 'clobber' target
# .clobber-post: called after 'clobber' target
# .all-pre: called before 'all' target
# .all-post: called after 'all' target
# .help-pre: called before 'help' target
# .help-post: called after 'help' target
#
# Targets beginning with '.' are not intended to be called on their own.
#
# Main targets can be executed directly, and they are:
#
# build build a specific configuration
# clean remove built files from a configuration
# clobber remove all built files
# all build all configurations
# help print help mesage
#
# Targets .build-impl, .clean-impl, .clobber-impl, .all-impl, and
# .help-impl are implemented in nbproject/makefile-impl.mk.
#
# Available make variables:
#
# CND_BASEDIR base directory for relative paths
# CND_DISTDIR default top distribution directory (build artifacts)
# CND_BUILDDIR default top build directory (object files, ...)
# CONF name of current configuration
# CND_PLATFORM_${CONF} platform name (current configuration)
# CND_ARTIFACT_DIR_${CONF} directory of build artifact (current configuration)
# CND_ARTIFACT_NAME_${CONF} name of build artifact (current configuration)
# CND_ARTIFACT_PATH_${CONF} path to build artifact (current configuration)
# CND_PACKAGE_DIR_${CONF} directory of package (current configuration)
# CND_PACKAGE_NAME_${CONF} name of package (current configuration)
# CND_PACKAGE_PATH_${CONF} path to package (current configuration)
#
# NOCDDL
# Environment
MKDIR=mkdir
CP=cp
CCADMIN=CCadmin
# build
build: .build-post
.build-pre:
# Add your pre 'build' code here...
.build-post: .build-impl
# Add your post 'build' code here...
# clean
clean: .clean-post
.clean-pre:
# Add your pre 'clean' code here...
.clean-post: .clean-impl
# Add your post 'clean' code here...
# clobber
clobber: .clobber-post
.clobber-pre:
# Add your pre 'clobber' code here...
.clobber-post: .clobber-impl
# Add your post 'clobber' code here...
# all
all: .all-post
.all-pre:
# Add your pre 'all' code here...
.all-post: .all-impl
# Add your post 'all' code here...
# build tests
build-tests: .build-tests-post
.build-tests-pre:
# Add your pre 'build-tests' code here...
.build-tests-post: .build-tests-impl
# Add your post 'build-tests' code here...
# run tests
test: .test-post
.test-pre:
# Add your pre 'test' code here...
.test-post: .test-impl
# Add your post 'test' code here...
# help
help: .help-post
.help-pre:
# Add your pre 'help' code here...
.help-post: .help-impl
# Add your post 'help' code here...
# include project implementation makefile
include nbproject/Makefile-impl.mk
# include project make variables
include nbproject/Makefile-variables.mk

Answer 1

You have to tell the linker where to find the symbol.
For example:
g++ -c phrase.cpp # creates phrase.o which defines phrase_init()
g++ -c main.cpp # creates main.o which refers to phrase_init()
g++ phrase.o main.o -o main # creates executable file "main"
Or, to do all of the above in one command:
g++ phrase.cpp main.cpp -o main
Note that I'm assuming both source files are C++, and are named with .cpp extensions. Your question refers to files with both .c and .cpp extensions, and the question is tagged c++.
If you're using C, then you shouldn't be using C++-specific headers in main.c, and you should use gcc rather than g++.
If you're using C++, all your source files should have .cpp suffixes and you should used g++.
And if you're trying to mix C and C++, then you should be using extern "C" so the compiler knows what you're doing (but it's usually easier to use pure C++).

Answer 2

And you really should compile with -Wall -g so add to your Makefile
CXXFLAGS+= -Wall -g
CFLAGS+= -Wall -g
the first is for C++, the second is for C
I also think you should write by hand your own (simpler) Makefile for make (instead of copying a more complex Makefile that you don't understand).