Compilare: user.cpp: In function ‘void prefibo(int)’: user.cpp:44:43: warning: operation on ‘k’ may be undefined [-Wsequence-point] fib[++k] = fib[k - 1] + fib[k - 2]; ^ user.cpp:44:43: warning: operation on ‘k’ may be undefined [-Wsequence-point] user.cpp:41:16: warning: unused variable ‘c’ [-Wunused-variable] int k = 3, c=0; ^ user.cpp: In function ‘int main()’: user.cpp:61:9: warning: unused variable ‘k’ [-Wunused-variable] int k = 1; ^ user.cpp:55:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &n); ^