잘 돌아가던 프로그램이었는데
컴파일 하니 에러가 납니다 ㅠㅠ

[C++ Error] _stddef.h(37): E2141 Declaration syntax error
  [C++ Error] _stddef.h(133): E2090 Qualifier 'std' is not a class or namespace name
  [C++ Error] _stddef.h(133): E2272 Identifier expected
  [C++ Error] _stddef.h(134): E2090 Qualifier 'std' is not a class or namespace name
  [C++ Error] _stddef.h(134): E2272 Identifier expected
  [C++ Error] _stddef.h(135): E2090 Qualifier 'std' is not a class or namespace name
  [C++ Error] _stddef.h(135): E2272 Identifier expected
  [C++ Error] _stddef.h(136): E2090 Qualifier 'std' is not a class or namespace name
  [C++ Error] _stddef.h(136): E2272 Identifier expected
  [C++ Error] mem.h(37): E2188 Expression syntax
  [C++ Error] mem.h(37): E2293 ) expected
  [C++ Error] mem.h(38): E2188 Expression syntax
  [C++ Error] mem.h(38): E2293 ) expected
  [C++ Error] mem.h(39): E2188 Expression syntax
  [C++ Error] mem.h(39): E2293 ) expected
  [C++ Error] mem.h(40): E2188 Expression syntax
  [C++ Error] mem.h(40): E2293 ) expected
  [C++ Error] mem.h(47): E2316 'size_t' is not a member of 'std'
  [C++ Error] mem.h(46): E2188 Expression syntax
  [C++ Error] mem.h(47): E2293 ) expected
  [C++ Error] mem.h(49): E2316 'size_t' is not a member of 'std'
  [C++ Error] mem.h(48): E2188 Expression syntax
  [C++ Error] mem.h(49): E2293 ) expected
  [C++ Error] mem.h(51): E2316 'size_t' is not a member of 'std'
  [C++ Error] mem.h(50): E2188 Expression syntax
  [C++ Error] mem.h(50): E2228 Too many error or warning messages

라고 나오면서
_stddef.h의
namespace std {                <======== 여기를 가리키네요..


이거 왜 이런 에러가 나는것이며 해결방법은 무엇인지 알려 주세요 ㅠㅠ