Compilare: user.cpp: In function ‘int main()’: user.cpp:131:9: warning: unused variable ‘l1’ [-Wunused-variable] int l1 = length (v1), l2 = length (v2); ^ user.cpp: In function ‘long long int first_val(long long int, long long int)’: user.cpp:75:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:79:51: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("infinitepatternmatching.in", "r", stdin); ^ user.cpp:80:53: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("infinitepatternmatching.out", "w", stdout); ^ user.cpp:82:37: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (sir + 1), L = strlen (sir + 1); ^ /tmp/cchFrP6C.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.