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Double To Int -- Coversions

compman9902
105 New Member
First of all, thank you for taking the time to look at my post.
My question is pretty plain: "How do I convert a double variable into an int variable?"

For example, say I have a double variable and its value is 88.92.
Then I have an empty int variable.
How would I make that int variable equal 88?
Would that same method work if the double variable equaled just 56?

Well, thank you for taking a look at my question(s).
Also, please include code with your post.
Again, Thank You.
Jul 23 '07 #1
5 1865
ilikepython
844 Recognized Expert Contributor
First of all, thank you for taking the time to look at my post.
My question is pretty plain: "How do I convert a double variable into an int variable?"

For example, say I have a double variable and its value is 88.92.
Then I have an empty int variable.
How would I make that int variable equal 88?
Would that same method work if the double variable equaled just 56?

Well, thank you for taking a look at my question(s).
Also, please include code with your post.
Again, Thank You.
That's pretty simple:
Expand|Select|Wrap|Line Numbers
  1. double num = 88.92;
  2. int x = num;                   // gives a warning
  3. cout << x << endl;
  4. // or...
  5. double num = 88.92;
  6. int x = int(num);      // no warning
  7. cout << x << endl;
  8.  
Jul 23 '07 #2
compman9902
105 New Member
That's pretty simple:
Expand|Select|Wrap|Line Numbers
  1. double num = 88.92;
  2. int x = num;                   // gives a warning
  3. cout << x << endl;
  4. // or...
  5. double num = 88.92;
  6. int x = int(num);      // no warning
  7. cout << x << endl;
  8.  
Wow, thank you for getting back to my post so quickly.
It worked perfectly.
Jul 23 '07 #3
ilikepython
844 Recognized Expert Contributor
Wow, thank you for getting back to my post so quickly.
It worked perfectly.
Your welcome .
Jul 23 '07 #4
Benny the Guard
92 New Member
Be careful with double to int conversions. ints have a smaller max size then doubles so if the value is too high you will get some bad behaviour. In general casting like this is bad (although int to double is fine).
Jul 23 '07 #5
weaknessforcats
9,208 Recognized Expert Moderator Expert
Be careful with double to int conversions. ints have a smaller max size then doubles so if the value is too high you will get some bad behaviour. In general casting like this is bad (although int to double is fine).
Pay attention to what Benny says.

You cannot convert a double to an int. Int has no decimal places. If you cast, you force a truncation of the decimal portion.

You can avoid the cast by a) calling a function that you write that has a double argument and returns an int, pr b) use a stringstream.

Expand|Select|Wrap|Line Numbers
  1. double d = 88.62;
  2. stringstream ss;
  3. ss << d;
  4. int result;
  5. ss >> result;               //the 88
  6.  
Here the decimal point and the decimal placesare still in the stringstream. You culd have this logic inside a function such that after you get the 88 youcould skip over the decimal point and retrieve the decimal places as a second int sop you could determine whether the result should be 88.62 or 88.63.

As a rule, do no mix integers and floating point. Floating point is generally for scientific use where extreme accuracy is not required.
Jul 23 '07 #6

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