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POHow to figure out how many decimal digits are in a large double?
 

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  1. POHow to figure out how many decimal digits are in a large double?
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    <p>Hey so I'm making a function that returns the number of decimals, whole numbers, or TOTAL numbers there are, but have been unable to make it work with either of these ways:</p> <ul> <li><p><strong>multiplying by a really large number</strong> like 10 billion doesn't work because of the innacurate way computers store decimals, making 2.3 2.2999575697</p></li> <li><p>Using a <strong>StringStream</strong> to convert the number to a string and count the characters doesn't work because it requires you to set the stream to a precision which either takes away or adds unnecesary '0' characters if not set to the actual number of decimals</p></li> </ul> <p>So WHAT DO I DO NOW? somebody please help =( <strong>Thanks!</strong></p> <p>if you wanna see my function that converts the numb to a string here it is:</p> <pre><code>////////////////////// Numbs_Digits //////////////////////////////////////////////// template&lt;typename T&gt; int Numbs_Digits(T numb, int scope) { stringstream ss(stringstream::in| stringstream::out), ss2(stringstream::in| stringstream::out); unsigned long int length= 0; unsigned long int numb_wholes; ss2 &lt;&lt; (int)numb; numb_wholes = ss2.str().length(); ss2.flush(); bool all= false; ss.precision(11); // HOW DO I MAKE THE PRECISION NUMBER THE NUMBER OF DECIMALS? switch(scope){ case ALL: all = true; case DECIMALS: ss &lt;&lt; fixed &lt;&lt; numb; length += ss.str().length()- (numb_wholes +1); // +1 for the "." if(all!= true) break; case WHOLE_NUMBS: length += numb_wholes; if(all!= true) break; default: break;} return length;}; </code></pre>
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    1. COInstead of giving us your sample code, it might be better if you could give a clearer description of the problem. Please gives some examples of numbers and the results you expect.
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      1. POHow to figure out how many decimal digits are in a large double?
      1. USAaron McDaid
    2. COJudging from your previous questions, I'd recommend reading up on how floating point actually works. Then you will understand why "the number of decimals in a double" doesn't make much sense.
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    3. COPossible dupe of http://stackoverflow.com/questions/4738768/printing-double-without-losing-precision
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      1. USThomasMcLeod
 

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