foo.cc:148:9: error: ISO C++ forbids declaration of 'ReSize' with no type [-fpermissive]
  148 |  ReSize()
      |         ^
foo.cc: In member function 'int BigIntArray::ReSize()':
foo.cc:157:7: warning: control reaches end of non-void function [-Wreturn-type]
  157 |   data=newdata;
      |   ~~~~^~~~~~~~

[Hydro](https://hydro.ac)提供评测服务