C header file include error
Hopefully this is a straightforward question... Here's my process to reproduce this issue. First I create my source file:
bash $ cat t.c
#include "t.h"
int main()
{
ABC abc;
}
Then I create my corresponding header file:
bash $ cat t.h
#ifdef _T_H
#define _T_H
#ifdef __cplusplus
extern "C" {
#endif
typedef struct abc {
int a;
} ABC;
#ifdef __cplusplus
}
#endif
#endif
Then, I try to compile it:
bash $ gcc -o t t.c
t.c: In function ‘main’:
t.c:5: error: ‘ABC’ undeclared (first use in this function)
t.c:5: error: (Each undeclared identifier is reported only once
t.c:5: error: for each function it appears in.)
t.c:5: error: expected ‘;’ before ‘abc’
What is going on? If I use 'struct abc' instead of 'ABC' as the type in t.c, then it does compile. Why aren开发者_运维知识库't the typedefs working?
Try:
#ifndef _T_H
#define _T_H
I happened to notice this because the _T_H
didn't line up, and my subconscious brain knew it should.
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