Compilare: main.cpp: In function 'int main()': main.cpp:16:42: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] if (c=='*'&&Top>0) {v[Top-1]=NULL;Top--;} ^~~~ main.cpp:19:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<=strlen (v);j++) ~^~~~~~~~~~~~ main.cpp:21:83: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] if ((w[Top-1]=='('&&v[j]==')')||(w[Top-1]=='['&&v[j]==']')) {w[Top-1]=NULL;Top--;} ^~~~ main.cpp:24:19: warning: NULL used in arithmetic [-Wpointer-arith] if (w[0]==NULL) fout<<":)"<<endl; else fout<<":("<<endl; ^~~~ main.cpp:26:42: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] for(j=0;j<=Top;j++) w[j]=NULL; ^~~~ main.cpp:27:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<=strlen(v);j++) v[j]=NULL; ~^~~~~~~~~~~ main.cpp:27:48: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] for(j=0;j<=strlen(v);j++) v[j]=NULL; ^~~~