code in unix and windows (unsigned int value problem)

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C++

int main(int argc, char* argv[])
{
  unsigned long long x=atoi(argv[1]);
  unsigned long long y=atoi(argv[2]);
  if(x>0 && x<=4294967295 && y>0 && y<=4294967295)
  {
    cout<<"done";
  }
  else
  {
    cout<<"not done";
  }
  return 0;
}

But when i insert x=6543848485 or any value greater than 2254354363(10 digit), it is automatically taking the default value of x=2147483647(automatically). I don't know why? and not entering in the else condition.

But when i run this code in windows i.e. in dev-cpp it is running. but i want to run it in unix.

help

Posted 4-Sep-11 22:32pm

Trick7

Updated 4-Sep-11 22:40pm

Prerak Patel

v2

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OriginalGriff · Answer 1 · 2011-09-04T22:37:00

Solution 1

When you asked this question an hour ago, you got answers. taking default value of unsigned long int in unix[^]

The answer hasn't changed because you post it again.

Go back, read the answers and go from there - do not re-post your question, aask for clarification of an answer if you don't understand it.

Posted 4-Sep-11 22:37pm

OriginalGriff

Comments

Trick7 5-Sep-11 4:42am

Yes please clarify me y is it so???

OriginalGriff 5-Sep-11 4:53am

Because atoi returns an integer (that's what the 'i' on the end means). If the number does not fit in an integer, the returned result is "undefined" - which means that the library writer is free to do what they think sensible - in this case, it returns the maximum value that can be stored in a 32 bit integer - 2147483647 or 7FFFFFFF in hex.

Try instead using atol - it returns a long int which may be bigger on your target. Note that the size of an integer is not fixed in C or C++ as it is in .NET (it could be 16 bits, 32 bits, 24 bits, 64 bits or whatever is suitable for the target OS / processor)

[edit]minor typo, missed a ')' - OriginalGriff[/edit]

Trick7 5-Sep-11 4:58am

But it is runnning in dev-cpp compilor in windows... how???

OriginalGriff 5-Sep-11 5:10am

Because Microsoft C++ also supports the Int64 datatype (http://msdn.microsoft.com/en-us/library/s3f49ktz(v=vs.71).aspx) which you have probably got set as the default size, somewhere! Since this holds 64 bits rather than 32, your larger numbers fit in ok.
Your Unix compiler is using 32 bit intgers, which cannot contain a number bigger than 2147483647