Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:25:32: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive] freopen(input_file, 'r', stdin); ^ In file included from /usr/include/c++/4.8/cstdio:42:0, from /usr/include/c++/4.8/ext/string_conversions.h:43, from /usr/include/c++/4.8/bits/basic_string.h:2815, from /usr/include/c++/4.8/string:52, from /usr/include/c++/4.8/bits/locale_classes.h:40, from /usr/include/c++/4.8/bits/ios_base.h:41, from /usr/include/c++/4.8/ios:42, from /usr/include/c++/4.8/ostream:38, from /usr/include/c++/4.8/iostream:39, from user.cpp:1: /usr/include/stdio.h:279:14: error: initializing argument 2 of ‘FILE* freopen(const char*, const char*, FILE*)’ [-fpermissive] extern FILE *freopen (__const char *__restrict __filename, ^ user.cpp:26:34: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive] freopen(output_file, 'w', stdout); ^ In file included from /usr/include/c++/4.8/cstdio:42:0, from /usr/include/c++/4.8/ext/string_conversions.h:43, from /usr/include/c++/4.8/bits/basic_string.h:2815, from /usr/include/c++/4.8/string:52, from /usr/include/c++/4.8/bits/locale_classes.h:40, from /usr/include/c++/4.8/bits/ios_base.h:41, from /usr/include/c++/4.8/ios:42, from /usr/include/c++/4.8/ostream:38, from /usr/include/c++/4.8/iostream:39, from user.cpp:1: /usr/include/stdio.h:279:14: error: initializing argument 2 of ‘FILE* freopen(const char*, const char*, FILE*)’ [-fpermissive] extern FILE *freopen (__const char *__restrict __filename, ^ user.cpp:29:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < T; i++) ^ user.cpp:25:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(input_file, 'r', stdin); ^ user.cpp:26:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(output_file, 'w', stdout); ^