Compilare: main.cpp: In function 'int main()': main.cpp:102:15: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] b[lgbb+1]=NULL; ^~~~ main.cpp:111:22: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] c[j]=NULL; ^~~~ main.cpp:113:22: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] d[j]=NULL; ^~~~ main.cpp:123:24: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] d[lennr+1]=NULL; ^~~~ main.cpp:133:22: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] d[j]=NULL; ^~~~ main.cpp:137:24: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] d[lennr+1]=NULL; ^~~~ main.cpp: In function 'bool mycmp(int, int)': main.cpp:26:1: warning: control reaches end of non-void function [-Wreturn-type] } ^