Compilare: user.cpp: In function ‘int main()’: user.cpp:63:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0 ; j < c.size() ; ++ j) ^ user.cpp:26:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("litere2.in","r",stdin); ^ user.cpp:28:17: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s1 + 1); ^ /tmp/cc4lSa1y.o: In function `main': user.cpp:(.text.startup+0x41): warning: the `gets' function is dangerous and should not be used.