c++ - How to create a variable size char array in VC++ -

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const int sizea = 600;  char sz[sizea];

above code works fine. below code segment cause errors. i'm working on visual studio 2005 - mfc application

cstring strfinal;  .......//strfinal value dynamically changing . .   const int size = strfinal.getlength(); char sz[size];

error 2 error c2057: expected constant expression
error 5 error c2070: 'char []': illegal sizeof operand
error 4 error c2133: 'sz' : unknown size error 3 error c2466: cannot allocate array of constant size 0

in current version of c++, arrays must have fixed size, specified compile-time constant. if need use run-time value, options are:

  • most portably, use dynamic array class such std::string or std::vector<char>;
  • use compiler supports c99 variable-length arrays non-standard extension;
  • wait year dynamic arrays (hopefully) introduced in c++14 (and perhaps wait bit longer compiler vendor catch up).

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