foo.c:8:13: error: unknown type name 'BigInt'; did you mean 'int'?
 void Output(BigInt* p);
             ^~~~~~
             int
foo.c:9:10: error: unknown type name 'BigInt'; did you mean 'int'?
 void Mul(BigInt* p, int x);
          ^~~~~~
          int
foo.c:11:10: error: unknown type name 'BigInt'; did you mean 'int'?
 void Add(BigInt* p1, BigInt* p2, BigInt* pAns);
          ^~~~~~
          int
foo.c:11:22: error: unknown type name 'BigInt'; did you mean 'int'?
 void Add(BigInt* p1, BigInt* p2, BigInt* pAns);
                      ^~~~~~
                      int
foo.c:11:34: error: unknown type name 'BigInt'; did you mean 'int'?
 void Add(BigInt* p1, BigInt* p2, BigInt* pAns);
                                  ^~~~~~
                                  int
foo.c: In function 'main':
foo.c:18:2: error: unknown type name 'BigInt'; use 'struct' keyword to refer to the type
  BigInt x1;
  ^~~~~~
  struct 
foo.c:19:4: error: request for member 'n' in something not a structure or union
  x1.n = 1; x1.digit[0] = 1;   // 初始化为1
    ^
foo.c:19:14: error: request for member 'digit' in something not a structure or union
  x1.n = 1; x1.digit[0] = 1;   // 初始化为1
              ^
foo.c:20:27: warning: implicit declaration of function 'Mul' [-Wimplicit-function-declaration]
  for (i = 1; i <= m; i++) Mul(&x1, a);
                           ^~~
foo.c:22:2: error: unknown type name 'BigInt'; use 'struct' keyword to refer to the type
  BigInt x2;
  ^~~~~~
  struct 
foo.c:23:4: error: request for member 'n' in something not a structure or union
  x2.n = 1; x2.digit[0] = 1;   // 初始化为1
    ^
foo.c:23:14: error: request for member 'digit' in something not a structure or union
  x2.n = 1; x2.digit[0] = 1;   // 初始化为1
              ^
foo.c:26:2: error: unknown type name 'BigInt'; use 'struct' keyword to refer to the type
  BigInt x3;
  ^~~~~~
  struct 
foo.c:27:2: warning: implicit declaration of function 'Add' [-Wimplicit-function-declaration]
  Add(&x1, &x2, &x3);
  ^~~
foo.c:28:2: warning: implicit declaration of function 'Output' [-Wimplicit-function-declaration]
  Output(&x3);
  ^~~~~~
foo.c: At top level:
foo.c:32:10: error: unknown type name 'BigInt'; did you mean 'int'?
 void Add(BigInt* p1, BigInt* p2, BigInt* pAns)
          ^~~~~~
          int
foo.c:32:22: error: unknown type name 'BigInt'; did you mean 'int'?
 void Add(BigInt* p1, BigInt* p2, BigInt* pAns)
                      ^~~~~~
                      int
foo.c:32:34: error: unknown type name 'BigInt'; did you mean 'int'?
 void Add(BigInt* p1, BigInt* p2, BigInt* pAns)
                                  ^~~~~~
                                  int
foo.c:59:10: error: unknown type name 'BigInt'; did you mean 'int'?
 void Mul(BigInt* p, int x)
          ^~~~~~
          int
foo.c:75:13: error: unknown type name 'BigInt'; did you mean 'int'?
 void Output(BigInt* p)
             ^~~~~~
             int
foo.c: In function 'main':
foo.c:16:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &a, &m);
  ^~~~~~~~~~~~~~~~~~~~~
foo.c:17:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &b, &n);
  ^~~~~~~~~~~~~~~~~~~~~

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