Compilare: main.cpp: In function 'int main()': main.cpp:93:15: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] b[lgbb+1]=NULL; ^~~~ main.cpp:104:22: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] c[j]=NULL; ^~~~ main.cpp:107:22: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] d[j]=NULL; ^~~~ main.cpp:122:24: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] d[lennr+1]=NULL; ^~~~ main.cpp:135:22: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] d[j]=NULL; ^~~~ main.cpp:142:24: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] d[lennr+1]=NULL; ^~~~