add.h

#define _CRT_SECURE_NO_WARNINGS 1
#define NULL 0
#define EOF (-1)
#define BUFSIZ 1024
#define OPEN_MAX 20
typedef struct _iobuf {
    int cnt;
    char* ptr;
    char* base;
    int flag;
    int fd;
} FILE;
enum flags
{
    _READ = 01,
    _WRITE = 02,
    _UNBUF = 04,
    _EOF = 010,
    _ERR = 020
};
FILE ZZ[OPEN_MAX]= {
    { 0,(char*)0,(char*)0 ,_READ,0 },
    { 0,(char*)0,(char*)0 ,_WRITE,1 },
    { 0,(char*)0,(char*)0 ,_WRITE | _UNBUF,2 }
};
#define stdin (&ZZ[0])
#define stdout (&ZZ[1])
#define stderr (&ZZ[2])
#define gaa__getchar() getc(stdin)
#define putchar(x) putc((x),stdout)
#define feof(p)     (((p)->flag & _EOF)!=0 )
#define ferror(p)   (((p)->flag & _EOF)!=0 )
#define fileno(p)   ((p)->fd)
#define getc(p) (--(p)->cnt >=0 ? (unsigned char)*(p)->ptr++: _fillbuf(p))
#define putc(x,p) (--(p)->cnt >=0 ? *(p)->ptr++ = (x) : _flushbuf((x),p) )

#define _CRT_SECURE_NO_WARNINGS 1
#include "add.h"
extern FILE ZZ[OPEN_MAX];



#define _S_IREAD  0x0100 // Read permission, owner
#define _S_IWRITE 0x0080 // Write permission, owner



FILE* fopen(char* name, char* mode)
{

    return NULL;
}

int _fillbuf(FILE* fp)
{
 
    return NULL;
}

extern FILE* fopen(char* name, char* mode);

int main(int argc, char* argv[])
{
     //FILE* f = fopen(argv[1], "r");
     //char c = gaa__getchar();
    return 0;
}

#include "add.h"
extern FILE* fopen(char* name, char* mode);

int main(int argc, char* argv[])
{
     //FILE* f = fopen(argv[1], "r");
     //char c = gaa__getchar();
    return 0;
}

#define stdin (&ZZ[0])
#define stdout (&ZZ[1])
#define stderr (&ZZ[2])
#define gaa__getchar() getc(stdin)
#define putchar(x) putc((x),stdout)