Adding JString

Hey there I'm new in this forum. I'm a noob at coding in C++, and I'm trying to code a DLL to be loaded in Java.

There a portion of my code, very simple:

Code:

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JNIEXPORT jstring JNICALL Java_test_addString(JNIEnv *obj, jclass, jstring a, jstring b){
        jstring c = obj->NewStringUTF((char*)obj->GetStringUTFChars(a,0));
        jstring d = obj->NewStringUTF((char*)obj->GetStringUTFChars(b,0));
        //...
        return c+d;
}

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Usually you can add 2 strings with '+' operator. But in this particular case, I'm going off my rocker. Apparently I can't add 2 strings in that way. I would use some enum\integral types, but dunno how to do that.

Hope you can help me.
Thank you for your attention.

I found out a solution, only. Shortly I use 'strcat', and it works now.
But is there other ways to do the same thing? I ask.