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갑자기 컴파일시 이런 오류가 발생하네요
문제 무엇인지 모르겠습니다.
고수님들의 조언 부탁드립니다.
좀 급합니다.

[C++ Error] _stddef.h(36): E2141 Declaration syntax error
[C++ Error] _stddef.h(132): E2090 Qualifier 'std' is not a class or namespace name
[C++ Error] _stddef.h(132): E2272 Identifier expected
[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] 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(41): E2188 Expression syntax
[C++ Error] mem.h(41): E2293 ) expected
[C++ Error] mem.h(42): E2188 Expression syntax
[C++ Error] mem.h(42): 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(51): E2293 ) expected
[C++ Error] mem.h(53): E2316 'size_t' is not a member of 'std'
[C++ Error] mem.h(52): E2188 Expression syntax
[C++ Error] mem.h(52): E2228 Too many error or warning messages