Compilare: main.cpp: In function 'bool egal(int, int)': main.cpp:17:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=0;k<strlen(v[i]);++k) if(v[i][k]!=v[j][k]) return 0; ~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:42:18: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] s[n]=NULL; ^~~~ main.cpp:99:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<strlen(v[i]);++j) g<<v[i][j]; ~^~~~~~~~~~~~~