Question

In a code I have 2 CString which contain a part of version number,
First exe contain version 1.1234.3.1 and the second exe has version 1.2.3.1.

Code should be such that

Suppose

CString MinVreg,MinFref;

if(MinVreg<MinFref) //when MinVreg="1234" and MinFref="2"

{
    //it enters in if loop.
    //Update registry
}
elseif(MinVreg>MinFref)
{
   //Show message box..
}

I think the operator check only first digit.So please tell me how to compare it as a number

Answer 1

You have to parse the strings to represent a version as an integer array, then perform a lexicographic compare.

bool ParseVersionString(unsigned digits[4], const CString& i_version)
  {
  return sscanf(i_version, "%d.%d.%d.%d", &digits[0], &digits[1], 
                &digits[2], &digits[3]) == 4;
  }

int CompareVersions(unsigned ver1[4], unsigned ver2[4])
  {
  for (int i = 0; i != 4; ++i)
    {
    if (ver1[i] < ver2[i])
      return -1;
    if (ver1[i] > ver2[i])
      return 1;
    }

  return 0;
  }

Usage:

  CString MinVreg("1.1234.3.1"), MinFref("1.2.3.1");
  unsigned ver1[4], ver2[4];
  if (ParseVersionString(ver1, MinVreg) &&
      ParseVersionString(ver2, MinFref) &&
      CompareVersions(ver1, ver2) < 0)
  {
  //Update registry
  }