4 ms·

The more I look at Fortran, the more I appreciate its beauty. I think some of its infamy is unjustified.

by didip 7y ago

acqq 7y ago
My contribution to an example of something done right in the first FORTRAN and then done wrong many times afterwards: "The March of Progress > * 1956: Fortran I: > PRINT 1, X > 1 FORMAT (F10.2) * 1980: C printf("%10.2f", x); * 1988: C++ cout << setw(10) << setprecision(2) << showpoint << x; * 1996: Java java.text.NumberFormat formatter = java.text.NumberFormat.getNumberInstance(); formatter.setMinimumFractionDigits(2); formatter.setMaximumFractionDigits(2); String s = formatter.format(x); for (int i = s.length(); i < 10; i++) System.out.print(' '); System.out.print(s); * 2004: Java System.out.printf("%10.2f", x); * 2008: Scala and Groovy printf("%10.2f", x) " The reference and the details (2012): https://news.ycombinator.com/item?id=3964475 https://news.ycombinator.com/item?id=3964475
- nwallin 7y ago
  In my work life, I have a problem where I have to interface with a stringly typed API. For instance, characters 20-25 in a 400 byte string are a floating point number. No it's not a good API but I don't make decisions. So you need a six character float. "12" is wrong because it's two characters, also "12<four spaces>" is invalid. "1.2e01" is wrong compared to "12.000" because it has (many) more significant digits. ".00001" is wrong compared to "1.2e-5". I don't know how to solve this problem. printf doesn't cut it. It simply can't specify an exact number of characters.
  - BeeOnRope 7y ago
    You could try: %06.*g for width 6 down to 1. I believe this will always find an answer, and the one with the largest number of significant digits. For example: void format(double val, int width, char* buf) { for (int w = width; w > 0; w--) { int count = sprintf(buf, "%06.*g", w, val); if (count == width) return; } } "Working" example (unsafe, exits on failure, etc): https://godbolt.org/z/WiaPkT https://godbolt.org/z/WiaPkT Note that you can't represent negative values equal or below -1e-100 since those take 7 characters.

The more I look at Fortran, the more I appreciate its beauty. I think some of its infamy is unjustified.

by didip 7y ago

The more I look at Fortran, the more I appreciate its beauty. I think some of its infamy is unjustified.

acqq 7y ago

My contribution to an example of something done right in the first FORTRAN and then done wrong many times afterwards: "The March of Progress > * 1956: Fortran I: > PRINT 1, X > 1 FORMAT (F10.2) * 1980: C printf("%10.2f", x); * 1988: C++ cout << setw(10) << setprecision(2) << showpoint << x; * 1996: Java java.text.NumberFormat formatter = java.text.NumberFormat.getNumberInstance(); formatter.setMinimumFractionDigits(2); formatter.setMaximumFractionDigits(2); String s = formatter.format(x); for (int i = s.length(); i < 10; i++) System.out.print(' '); System.out.print(s); * 2004: Java System.out.printf("%10.2f", x); * 2008: Scala and Groovy printf("%10.2f", x) " The reference and the details (2012): https://news.ycombinator.com/item?id=3964475 https://news.ycombinator.com/item?id=3964475

nwallin 7y ago
In my work life, I have a problem where I have to interface with a stringly typed API. For instance, characters 20-25 in a 400 byte string are a floating point number. No it's not a good API but I don't make decisions. So you need a six character float. "12" is wrong because it's two characters, also "12<four spaces>" is invalid. "1.2e01" is wrong compared to "12.000" because it has (many) more significant digits. ".00001" is wrong compared to "1.2e-5". I don't know how to solve this problem. printf doesn't cut it. It simply can't specify an exact number of characters.
- BeeOnRope 7y ago
  You could try: %06.*g for width 6 down to 1. I believe this will always find an answer, and the one with the largest number of significant digits. For example: void format(double val, int width, char* buf) { for (int w = width; w > 0; w--) { int count = sprintf(buf, "%06.*g", w, val); if (count == width) return; } } "Working" example (unsafe, exits on failure, etc): https://godbolt.org/z/WiaPkT https://godbolt.org/z/WiaPkT Note that you can't represent negative values equal or below -1e-100 since those take 7 characters.