Compilare: user.cpp: In function ‘int main()’: user.cpp:22:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(a)) ^ user.cpp:17:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(s_file1, "%s", a); ^ user.cpp:18:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(s_file1, "%s", b); ^