Compilare: user.cpp: In function ‘int main()’: user.cpp:17:20: warning: NULL used in arithmetic [-Wpointer-arith] while (p[i] != NULL) ^~~~ user.cpp:25:51: warning: NULL used in arithmetic [-Wpointer-arith] if (p[i] >= '0' && p[i] <= '9' && p[i] != NULL) ^~~~ user.cpp:27:61: warning: NULL used in arithmetic [-Wpointer-arith] if (p[i+1] >= '0' && p[i+1] <= '9' && p[i+1] != NULL) ^~~~ user.cpp:34:20: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] v[0] = NULL; ^~~~ user.cpp:40:24: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] v[++cnt] = NULL; ^~~~ user.cpp:49:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0; j<strlen(v); j++) ~^~~~~~~~~~ user.cpp:54:27: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] a[n][m] = NULL; ^~~~