Compilare: user.cpp: In function ‘int main()’: user.cpp:27:10: warning: unused variable ‘sum’ [-Wunused-variable] int n, sum, dif, a, b; ^ user.cpp:27:15: warning: unused variable ‘dif’ [-Wunused-variable] int n, sum, dif, a, b; ^ user.cpp:27:20: warning: unused variable ‘a’ [-Wunused-variable] int n, sum, dif, a, b; ^ user.cpp:27:23: warning: unused variable ‘b’ [-Wunused-variable] int n, sum, dif, a, b; ^ user.cpp:29:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &n); ^