Compilare: user.cpp: In function ‘int main()’: user.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(c);i++) ^ user.cpp:19:26: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(c , 1700 , fin); ^