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Old 06-24-2020, 01:35 PM   #1
bkelly
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Registered: Jan 2008
Distribution: Centos 7-4
Posts: 205

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printf formatting for doubles


Centos, c++
Please accomodate typos as I cannot copy from my computer to here and am quite subject to little errors.
This write statement typifies the writes to a file:

Code:
fprintf( multi_column_file, %03.3f,  %03.3f,  %03.3f, a, b, c);
All numbers are less than 100.0 but the columns are not lined up. %4d seems to work fine with integers, but this does not work with doubles.
What needs to be done differently?
 
Old 06-24-2020, 02:07 PM   #2
shruggy
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Registered: Mar 2020
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%3.3f means three-character-wide field, and yet three are digits after the decimal point. Including the decimal point itself you already have four characters which is more than the whole field width. No wonder the fields are not aligned. To accommodate 100.0 you'll need at least %5.1f. In other words
Code:
3(integer part)+1(decimal point)+1(fractional part)=5

Last edited by shruggy; 06-24-2020 at 02:23 PM.
 
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Old 06-24-2020, 02:22 PM   #3
bkelly
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Registered: Jan 2008
Distribution: Centos 7-4
Posts: 205

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shruggy is correct. I was thinking %3.4 meant three characters to the left of the decimal point and four to the right. I switched to %8.4 and all is good.
Thank you for your time.
 
  


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