指针和realloc的问题，C中的程序崩溃错误

In main.c

#include <stdio.h>
#include "poly.h"

int main (void)
{
  struct poly *p0 = polySetCoefficient (polySetCoefficient (polySetCoefficient (polyCreate() , 0, 4.0), 1, -1.0), 10, 2.0);

  //polyPrint (p0);

  return 0;
}
#include <stdio.h>
#include "poly.h