sms.cpp: In function 'int main()': sms.cpp:31: warning: comparison between signed and unsigned integer expressions sms.cpp:50: warning: comparison between signed and unsigned integer expressions sms.cpp:21: warning: unused variable 'pos' sms.cpp:18: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sms.cpp:18: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result