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c++ – Unable to include iostream in android why?

Posted by: admin June 15, 2020 Leave a comment

Questions:

Have installed android-ndk-r7, and trying to compile .cpp file.

#include <iostream>

using namespace std;

int main ( int argc, char ** argv)
{

     cout <<"Hello World.."<<endl;

} 

Executed following command:
Got into jni folder, and executed

#ndk-build

Got following error:

/home/jelari/Desktop/androidDevelopment/android-ndk-r7/DCF/jni/test1.cpp:1:20: error: iostream: No such file or directory
/home/jelari/Desktop/androidDevelopment/android-ndk-r7/DCF/jni/test1.cpp: In function 'int main(int, char**)':
/home/jelari/Desktop/androidDevelopment/android-ndk-r7/DCF/jni/test1.cpp:8: error: 'cout' was not declared in this scope
/home/jelari/Desktop/androidDevelopment/android-ndk-r7/DCF/jni/test1.cpp:8: error: 'endl' was not declared in this scope
make: *** [/home/jelari/Desktop/androidDevelopment/android-ndk-r7/DCF/obj/local/armeabi/objs/test1/test1.o] Error 1

What am i doing wrong ?

My Android.mk file looks like:

# A simple test for the minimal standard C++ library
#

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE := test1
LOCAL_SRC_FILES := test1.cpp
include $(BUILD_EXECUTABLE)

and Application.mk file looks like:

# Build both ARMv5TE and ARMv7-A machine code.
APP_ABI := armeabi armeabi-v7a

Kindly point out the mistake?

How to&Answers:

Just so the answer is readily accessible here on SO, here it is:

By default, the C++ standard library is very minimal.

You need to set APP_STL in your Application.mk file.

I use:

APP_STL := gnustl_static

but you could have used system, stlport_static, stlport_shared, or
gnustl_static.

It’s documented under $NDK/docs/CPLUSPLUS-SUPPORT.html, and it’s a
little hidden, because the $NDK/documentation.html index file doesn’t
list it.

Quoted from http://groups.google.com/group/android-ndk/browse_thread/thread/983c436239d48704?pli=1

Answer:

Another way is that if you don’t have application.mk and android.mk file,

add this in your build.gradle

ndk{
    moduleName = your_module_name
    stl = "c++_static"
}

Answer:

I met this problem and just spent days to update my NDK from r10e to r20, there’re several variables are changed.

For NDK r10e

Android.mk:

include $(CLEAR_VARS)
LOCAL_MODULE := main
LOCAL_SRC_FILES := ./main.cpp   
LOCAL_C_INCLUDES += $(LOCAL_PATH)/
LOCAL_CPP_EXTENSION := .cxx .cpp .cc
LOCAL_CPPFLAGS := -fexceptions -frtti
LOCAL_CPPFLAGS += -std=c++11 -D__cplusplus=201103L
include $(BUILD_EXECUTABLE)

Application.mk:

APP_ABI := all
APP_STL := gnustl_static
NDK_TOOLCHAIN_VERSION := 4.9
APP_OPTIM := debug

For NDK r20

Android.mk:

include $(CLEAR_VARS)
LOCAL_MODULE := main
LOCAL_SRC_FILES := ./main.cpp   
LOCAL_C_INCLUDES += $(LOCAL_PATH)/
LOCAL_CPP_EXTENSION := .cxx .cpp .cc
LOCAL_CPPFLAGS := -fexceptions -frtti
LOCAL_CPPFLAGS += -std=c++11 -D__cplusplus=201103L -DANDROID_STL=c++_shared
include $(BUILD_EXECUTABLE)

Application.mk:

APP_ABI := all
#In general, you can only use a static variant of the C++ runtime if you have one and only one shared library in your application.
APP_STL := c++_static
NDK_TOOLCHAIN_VERSION := clang
APP_PLATFORM := android-23
APP_OPTIM := debug

and my main.cpp (including my bin_node.h):

int main(int argc,char **argv) {   
printf("****************** tree node ******************\n");
amo::BinNode<int> root(0);
amo::BinNode<int>* lchild1 = root.insertLeftChild(1);
amo::BinNode<int>* rchild2 = root.insertRightChild(2);
amo::BinNode<int>* lchild3 = lchild1->insertLeftChild(3);
amo::BinNode<int>* rchild4 = lchild1->insertRightChild(4);
amo::BinNode<int>* lchild5 = rchild2->insertLeftChild(5);
amo::BinNode<int>* rchild6 = rchild2->insertRightChild(6);
amo::BinNode<int>* lchild7 = lchild3->insertLeftChild(7);
amo::BinNode<int>* rchild8 = lchild3->insertRightChild(8);
amo::BinNode<int>* lchild9 = rchild6->insertLeftChild(9);
amo::BinNode<int>* rchild10 = rchild6->insertRightChild(10);
amo::BinNode<int>* lchild11 = rchild8->insertLeftChild(11);
amo::BinNode<int>* rchild12 = rchild8->insertRightChild(12);

printf("going to root.traversePre()\n");
root.traversePre();
printf("going to root.traversePreLoop()\n");
root.traversePreLoop();
printf("going to root.traversePreLoop2()\n");
root.traversePreLoop2();
printf("\n****************** main return ******************\n");
return 0;}

Run ndk-build and build an executable file

enter image description here

For more source code and information for this, check my GitHub