Compilare: user.cpp: In function ‘void Introduce(int, int)’: user.cpp:60:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < H[nr_1].size(); ++j) ^ user.cpp:66:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( j == H[nr_1].size() ) ^ user.cpp: In function ‘void Query()’: user.cpp:83:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < H[nr_1].size(); ++j) ^ user.cpp: In function ‘void Read_String()’: user.cpp:25:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &n); ^ user.cpp:28:18: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(aux); ^ user.cpp: In function ‘void Query()’: user.cpp:75:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(aux); lg = strlen(aux); ^ user.cpp: In function ‘int main()’: user.cpp:105:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &m); ^ /tmp/ccJdV9kJ.o: In function `Read_String()': user.cpp:(.text+0x6b): warning: the `gets' function is dangerous and should not be used.