How to print log in android c++ file?

Question

I added

#define LOG_NDEBUG 0
#define LOG_TAG "StagefrightMediaScanner"
#include <utils/Log.h>

in the libstagefright/StagefrightMediaScanner.cpp

but can not print anything using LOGV and LOGE, does any other things can I need to do?

@Lucifer No, I am using android 4.0 source code to debug the framework's issue. — Victor S, Aug 28 '12 at 04:00
Possible duplicate of [What is the Log API to call from an Android JNI program?](https://stackoverflow.com/questions/5465941/what-is-the-log-api-to-call-from-an-android-jni-program) — Ciro Santilli OurBigBook.com, Nov 06 '17 at 09:46

score 55 · Accepted Answer · edited May 18 '22 at 07:16

55

You can use the following code to get Log

  __android_log_print(ANDROID_LOG_ERROR, "TRACKERS", "%s", Str);

and add the following header file

#include <android/log.h>

Additional docs are here: https://developer.android.com/ndk/reference/group/logging

edited May 18 '22 at 07:16

JoshuaMulliken

45
6

answered Dec 21 '12 at 07:01

Usman Kurd

7,212
7
57
86

what is Str in this case? Is it a variable, what will be its value – Shirish Herwade Sep 10 '14 at 11:49
__android_log_write() – kinORnirvana Jan 17 '17 at 11:19
Also need to modify Android.mk, add "LOCAL_LDLIBS :=-llog" – franny zhao Apr 25 '19 at 05:41

score 2 · Answer 2 · edited Apr 30 '15 at 07:10

You can check frameworks/av/media/libstagefright/Android.mk, whether there is

 LOCAL_SHARED_LIBRARIES += liblog

in it.

Then, under frameworks/av/media/libstagefright/

$ mm

$ adb push $OUT/system/lib/libstagefright.so /system/lib/ 

$ adb shell killall mediaserver

Then reboot your phone or am start a MEDIA_MOUNTED intent, MediaScanner will work, and the logs you just added(either ALOGE/ALOGV or LOGE/LOGV) should be shown.

score 0 · Answer 3 · answered Dec 21 '12 at 06:46

0

No you have done right. Just check it whether you are using ALOGV() which is similar to printf(),if you want to print a integer with a log then you can write like this :" ALOGV("Integer is %d",integer);".

answered Dec 21 '12 at 06:46

Tarun Chawla

508
4
17

score 0 · Answer 4 · edited Aug 30 '23 at 16:36

TestLog.cpp

{

#define LOG_VERBOSE(message, ...) ((void)__android_log_print(ANDROID_LOG_VERBOSE, "MY_LOG_TAG", "[%s %s] " message, __FILE_NAME__, __func__, ##__VA_ARGS__))


    void logFunction1() {
        char *testStatus = "Success";
        LOG_VERBOSE("This is my log, Status : %s", testStatus);
        logFunction2();
    }
    
    void logFunction2() {
        LOG_VERBOSE("Hope this is helpful !");
    }
}

output :

V [TestLog.cpp logFunction1] This is my log, Status : Success

V [TestLog.cpp logFunction2] Hope this is helpful !

How to print log in android c++ file?

4 Answers4