Main.cc: In function ‘int main()’: Main.cc:7:8: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(a);//gets¿ÉÒÔÓпոñ ^ In file included from /usr/include/stdio.h:862:0, from /usr/include/c++/7/cstdio:42, from /usr/include/c++/7/ext/string_conversions.h:43, from /usr/include/c++/7/bits/basic_string.h:6361, from /usr/include/c++/7/string:52, from /usr/include/c++/7/bits/locale_classes.h:40, from /usr/include/c++/7/bits/ios_base.h:41, from /usr/include/c++/7/ios:42, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/x86_64-linux-gnu/bits/stdio2.h:232:1: note: declared here gets (char *__str) ^~~~ Main.cc:8:10: error: ‘strlen’ was not declared in this scope int len=strlen(a); ^~~~~~ Main.cc:8:10: note: suggested alternative: ‘mbrlen’ int len=strlen(a); ^~~~~~ mbrlen Main.cc:13:51: error: ‘A’ was not declared in this scope else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ Main.cc: In lambda function: Main.cc:13:53: error: expected ‘{’ before ‘)’ token else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ Main.cc: In function ‘int main()’: Main.cc:13:48: error: no match for ‘operator>=’ (operand types are ‘char’ and ‘main()::’) else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ In file included from /usr/include/c++/7/bits/stl_algobase.h:64:0, from /usr/include/c++/7/bits/char_traits.h:39, from /usr/include/c++/7/ios:40, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/stl_pair.h:479:5: note: candidate: template constexpr bool std::operator>=(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&) operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) ^~~~~~~~ /usr/include/c++/7/bits/stl_pair.h:479:5: note: template argument deduction/substitution failed: Main.cc:13:53: note: mismatched types ‘const std::pair<_T1, _T2>’ and ‘char’ else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ In file included from /usr/include/c++/7/bits/stl_algobase.h:67:0, from /usr/include/c++/7/bits/char_traits.h:39, from /usr/include/c++/7/ios:40, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/stl_iterator.h:332:5: note: candidate: template bool std::operator>=(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&) operator>=(const reverse_iterator<_Iterator>& __x, ^~~~~~~~ /usr/include/c++/7/bits/stl_iterator.h:332:5: note: template argument deduction/substitution failed: Main.cc:13:53: note: mismatched types ‘const std::reverse_iterator<_Iterator>’ and ‘char’ else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ In file included from /usr/include/c++/7/bits/stl_algobase.h:67:0, from /usr/include/c++/7/bits/char_traits.h:39, from /usr/include/c++/7/ios:40, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/stl_iterator.h:370:5: note: candidate: template bool std::operator>=(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&) operator>=(const reverse_iterator<_IteratorL>& __x, ^~~~~~~~ /usr/include/c++/7/bits/stl_iterator.h:370:5: note: template argument deduction/substitution failed: Main.cc:13:53: note: mismatched types ‘const std::reverse_iterator<_Iterator>’ and ‘char’ else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ In file included from /usr/include/c++/7/bits/stl_algobase.h:67:0, from /usr/include/c++/7/bits/char_traits.h:39, from /usr/include/c++/7/ios:40, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/stl_iterator.h:1181:5: note: candidate: template bool std::operator>=(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&) operator>=(const move_iterator<_IteratorL>& __x, ^~~~~~~~ /usr/include/c++/7/bits/stl_iterator.h:1181:5: note: template argument deduction/substitution failed: Main.cc:13:53: note: mismatched types ‘const std::move_iterator<_IteratorL>’ and ‘char’ else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ In file included from /usr/include/c++/7/bits/stl_algobase.h:67:0, from /usr/include/c++/7/bits/char_traits.h:39, from /usr/include/c++/7/ios:40, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/stl_iterator.h:1187:5: note: candidate: template bool std::operator>=(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorL>&) operator>=(const move_iterator<_Iterator>& __x, ^~~~~~~~ /usr/include/c++/7/bits/stl_iterator.h:1187:5: note: template argument deduction/substitution failed: Main.cc:13:53: note: mismatched types ‘const std::move_iterator<_IteratorL>’ and ‘char’ else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ In file included from /usr/include/c++/7/string:52:0, from /usr/include/c++/7/bits/locale_classes.h:40, from /usr/include/c++/7/bits/ios_base.h:41, from /usr/include/c++/7/ios:42, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/basic_string.h:6208:5: note: candidate: template bool std::operator>=(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs, ^~~~~~~~ /usr/include/c++/7/bits/basic_string.h:6208:5: note: template argument deduction/substitution failed: Main.cc:13:53: note: mismatched types ‘const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>’ and ‘char’ else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ In file included from /usr/include/c++/7/string:52:0, from /usr/include/c++/7/bits/locale_classes.h:40, from /usr/include/c++/7/bits/ios_base.h:41, from /usr/include/c++/7/ios:42, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/basic_string.h:6221:5: note: candidate: template bool std::operator>=(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*) operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs, ^~~~~~~~ /usr/include/c++/7/bits/basic_string.h:6221:5: note: template argument deduction/substitution failed: Main.cc:13:53: note: mismatched types ‘const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>’ and ‘char’ else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ In file included from /usr/include/c++/7/string:52:0, from /usr/include/c++/7/bits/locale_classes.h:40, from /usr/include/c++/7/bits/ios_base.h:41, from /usr/include/c++/7/ios:42, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/basic_string.h:6233:5: note: candidate: template bool std::operator>=(const _CharT*, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) operator>=(const _CharT* __lhs, ^~~~~~~~ /usr/include/c++/7/bits/basic_string.h:6233:5: note: template argument deduction/substitution failed: Main.cc:13:53: note: mismatched types ‘const _CharT*’ and ‘char’ else if(a[i]<='z'&&a[i]>='a'||a[i]<='Z'&&a[i]>=[A]){ ^ Main.cc:7:6: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a);//gets¿ÉÒÔÓпոñ ~~~~^~~