undefined reference to `__android_log_print'

Question

What is wrong with my make file?

Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE    := foo
LOCAL_SRC_FILES := foo.c
LOCAL_EXPORT_LDLIBS := -llog
include $(BUILD_SHARED_LIBRARY)

foo.c

#include <string.h>
#include <jni.h>
#include <android/log.h>

#define  LOG_TAG    "foo"
#define  LOGI(...)  __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)

void test() {
    LOGI("test");
}

ndk-build

foo.c:9: undefined reference to `__android_log_print'

Modify line LOCAL_EXPORT_LDLIBS := -llog to LOCAL_LDLIBS := -llog — Shiv Buyya, Mar 11 '21 at 06:57

score 103 · Answer 1 · answered Jan 31 '11 at 05:46

103

You need to add

LOCAL_LDLIBS := -llog

to Android.mk

answered Jan 31 '11 at 05:46

Kyle

1,039
1
6
2

1

correct. if there are multiple libraries, need to add this statement for each one of them (after CLEAR VARS) – user13107 Jan 19 '16 at 04:17

score 94 · Accepted Answer · edited Jun 04 '13 at 12:57

94

Try the following in your Android.mk file:

LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog

edited Jun 04 '13 at 12:57

answered Dec 15 '10 at 23:29

Ryan Reeves

10,209
3
42
26

1

What is the necessary to add this? Would you Please explain in detail? – Dhasneem Mar 07 '13 at 12:40
its adding an android library to the make file - and it worked for me too – gheese Apr 24 '13 at 15:08
9

the -L is unnecessary. Please accept the other answer instead. – Jeff Allen Jun 21 '13 at 11:23
Why is the -L unnecessary? – Patrick Oct 10 '14 at 08:32
The -L is useful when you have subdirectories that build libraries. Otherwise, just having -llog works fine. – Bruce Oct 19 '14 at 16:18
The -L flag specifies an additional path that the linker should use to search for libraries. If `liblog` doesn't reside under `$(SYSROOT)/usr/lib` then it is unnecessary. – donturner Jun 03 '15 at 01:24
5

If using the new Gradle NDK integration in Android Studio 1.3, you need to add `ldLibs = ["android", "log"]` to your android.ndk options – Stephen Kaiser Sep 24 '15 at 04:20
@StephenKaiser unbelievable, I don't know how I noticed your comment, but you're THE SAVIOR – Anton Shkurenko Nov 25 '15 at 16:56
1

What if we are not using Android.mk's ? – cagdas Oct 27 '16 at 12:17
@cagdas for AS 2.2, stable plugin and CMake look at my [answer](http://stackoverflow.com/a/40512650/1979756) – lewkka Nov 09 '16 at 17:24

BoredT · Answer 3 · 2014-12-10T17:41:47.220

86

If you use Android Studio and gradle, it ignores Android.mk. Add this to your build.gradle file:

android {
    defaultConfig {
        ndk {
            moduleName "your_module_name"
            ldLibs "log"
        }
    }
}

edited Dec 10 '14 at 17:41

answered Dec 04 '14 at 14:58

BoredT

1,590
15
19

7

I wonder where this is documented. I was looking for this as well. – Randy Sugianto 'Yuku' Dec 19 '14 at 06:19
1

I was getting "undefined reference to '__android_log_print'" before I have added `ldLibs`. Thanks. – Denys Kniazhev-Support Ukraine Jan 02 '15 at 10:54
2

Adding this fixed it for me. Just make sure to add the `ndk` part in the build.gradle inside the `app` folder instead of the one in the project folder (module name). – mathiass Jun 06 '15 at 20:59
As of Gradle 2.5 use 'ldLibs += "log"' slight syntax change – Lorne K Oct 03 '15 at 00:00
15

this did NOT work for me. this is what I had to do: `ldLibs.addAll(["android", "log"])` – ᴛʜᴇᴘᴀᴛᴇʟ Feb 04 '16 at 07:09
Using the latest versions of everything as of 21-Jun-2016, the `ldLibs "log"` line fails for me with `Cause: org.gradle.api.internal.ExtensibleDynamicObject`. The `ldLibs.addAll` statement in the above comment works. I also tried `+=`, but that failed in a different way. – fadden Jun 21 '16 at 22:41

score 35 · Answer 4 · answered Nov 09 '16 at 17:22

35

For Android Studio 2.2 and tools.build:gradle:2.2.0 using CMake add or edit row in CMakeLists.txt:

target_link_libraries(<your_library_name> 
                      android 
                      log)

Thats connecting log library to yours.

answered Nov 09 '16 at 17:22

lewkka

1,019
15
25

score 16 · Answer 5 · answered May 05 '16 at 16:49

16

If you upgrade to Android Studio 2.1, above answers do not work, need use ldLibs.add() to load the lib as below:

android.ndk {
    moduleName = "[the_module_name]"
    ldLibs.addAll(['android', 'log'])
}

answered May 05 '16 at 16:49

DroidlikeCode

292
3
6

best modern (late 2017) answer – Sep 02 '17 at 00:37

score 12 · Answer 6 · answered Dec 14 '17 at 00:05

In case the project you are working on has the following characteristics that differ from other 'standard' answers:

Not using Android Studio
Not using gradle and the integrated CMake
No Android.mk or Application.mk used at all for build
Using CMake and the toolchain directly (maybe your project is Qt based and without using QtCreator neither)

The following target_link_libraries usage makes it:

    find_library(ANDROID_LOG_LIB log)
    target_link_libraries(${TARGET_NAME} ${ANDROID_LOG_LIB})

Being TARGET_NAMEthe name of the target to build (having set it up before with add_library or add_executable).

find_library is equally important as well as setting up the toolchain properly (use the toolchain provided by Android SDK at ANDROID_SDK_HOME/cmake/<version>/android.toolchain.cmake so it sets up CMAKE_SYSROOTwhich is used by find_ commands).

Only solution that helped me! Thanks a ton, I would extend it by a test if the library was found for better feedback to the developer as here https://stackoverflow.com/a/37868829/10030695 — ManuelTS, Jan 06 '19 at 15:02

score 7 · Answer 7 · answered Oct 09 '14 at 06:16

We can link a shared library in Android in 3 ways. In below 3 cases, the lines mentioned should be added in Android.mk

So here are the three ways.

1. LOCAL_LDLIBS way
LOCAL_LDLIBS := -llog

For some reason if 1 doesnt work(it did not work for me), You can try below 2 ways

2. LOCAL_LDFLAGS way
LOCAL_LDFLAGS := -llog

3. LOCAL_SHARED_LIBRARIES way
LOCAL_SHARED_LIBRARIES += liblog

Of course you also need to include #include <android/log.h> in your C/H file.

score 4 · Answer 8 · answered Sep 05 '14 at 21:17

Yes, you do need to add: LOCAL_LDLIBS := -llog as the other answers/comments have specified, however the original question did not specify if he use the jni library as: LOCAL_JNI_SHARED_LIBRARIES or as LOCAL_REQUIRED_MODULES.

I can pretty much say for sure that he has it used it as: LOCAL_REQUIRED_MODULES because of the LOCAL_EXPORT_LDLIBS := -llog in the question... unless that was added after an edit.

If you use LOCAL_REQUIRED_MODULES the shared library is installed in /system/lib instead of into the apk, because it is a required module. Therefore you will need to add LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog instead of just LOCAL_LDLIBS := -llog so that when the build system is building & linking the jni shared library, it will have the -llog definitions in the correct place, available to be built under $OUT/root/system/lib. Otherwise you will continue to get the same answer, even if you only add LOCAL_LDLIBS := -llog.

So, those who commented that the -L is not needed, and the other answer was correct, they were actually incorrect in this situation.

Thank you for actually explaining what's going on! – Richard Jul 27 '15 at 04:47 — Richard, Jul 27 '15 at 04:47

score 4 · Answer 9 · answered Nov 27 '15 at 01:40

In lieu with

If using the new Gradle NDK integration in Android Studio 1.3, you need to add ldLibs = ["android", "log"] to your android.ndk options – Stephen Kaiser Sep 24 at 4:20

use ldLibs.addAll(["android", "log"]) for the experimental plugin

score 3 · Answer 10 · answered Apr 15 '14 at 08:24

3

Add

LOCAL_SHARED_LIBRARIES:= \
        libbinder                       \
        liblog                          \

to Android.mk

answered Apr 15 '14 at 08:24

user3535040

31
1

3

Why? Please explain why this answer should work for the asker. – L0j1k Apr 15 '14 at 09:14

score 2 · Answer 11 · answered Mar 17 '20 at 09:47

2

-DCMAKE_CXX_FLAGS="-llog" helps me

answered Mar 17 '20 at 09:47

James

111
9

score 1 · Answer 12 · answered Aug 07 '15 at 12:12

1

This helped for me:

Android.mk

    LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_MODULE    := nativeDemo
LOCAL_SRC_FILES := main.cpp
LOCAL_LDLIBS += -llog

include $(BUILD_SHARED_LIBRARY)

answered Aug 07 '15 at 12:12

NickUnuchek

11,794
12
98
138

score 1 · Answer 13 · answered Jul 31 '20 at 12:56

TO build with Android.bp, follow the below solution:

In this -android_log_print is defined in NDK, so for this, there is already a library is available. Use "liblog" library using shared_libs tag, take reference of the below code:

target: {
        android: {
            cppflags: [
                "-g",
                "-DUSE_LIBLOG",
            ],
            shared_libs: ["liblog"], // can use other dependency if required.
        },
        darwin: {
            enabled: false,
        },
    },

score 1 · Answer 14 · answered Oct 26 '22 at 03:55

1

for the case who use CMakeLists.txt to make

    externalNativeBuild {
        cmake {
            path 'src/main/cpp/CMakeLists.txt'
        }
    }

just add -llog into target_link_libraries:

target_link_libraries(<your_library_name> -llog)

the env I used are :

gradle-6.5-all.zip

classpath 'com.android.tools.build:gradle:4.1.1'

Android Studio Arctic Fox | 2020.3.1 Patch 1 Build #AI-203.7717.56.2031.7621141, built on August 8, 2021

answered Oct 26 '22 at 03:55

VinceStyling

3,707
3
29
44

After scouring for hours, found the ONLY solution (your post) to make it work for CMakeLists.txt (all existing sources are for Android.mk). Added "target_link_libraries(native-lib -llog)" to CMakeLists.txt and PRESTO! I'm crying. Thank you! – ONE Feb 12 '23 at 19:14

Praveen Kumar KR · Answer 15 · 2017-09-28T04:21:55.920

In the android studio version 2.2 and higher, there is inbuilt support for CPP when you create a new project. Also, the liblog.so is included by default. Nothing to be done apart from including the header file (android/log.h).

Checkout app/CMakeLists.txt that is created by the studio when we create new android studio project. We can see that the find_library() block and target_link_libraries() block for loglib are already present.

Also, pay attention towards the function syntax. It should be:

__android_log_print (int priority, const char *tag, const char *fmt,...);

In my case, I had left out tag parameter and ended up spending good 3 days in figuring it out.

More about CMake: Add C and C++ Code to Your Project

score 0 · Answer 16 · edited Jul 03 '20 at 07:19

0

add LOCAL_SHARED_LIBRARIES:= liblog to Android.mk can solve my isuue. This is because the __android_log_print is defined in libLog

edited Jul 03 '20 at 07:19

jizhihaoSAMA

12,336
9
27
49

answered Jul 03 '20 at 06:47

nld2019

21
2

undefined reference to `__android_log_print'

16 Answers16

Linked