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I have some decimal numbers that I need to write to a text file with leading zeros when appropriate. I've done some research on this, and everything I've seen suggests something like:
REAL VALUE
INTEGER IVALUE
IF (VALUE.LT.0) THEN
IVALUE = CEILING(VALUE)
ELSE
IVALUE = FLOOR(VALUE)
ENDIF
WRITE(*,1) IVALUE, ABS(VALUE)-ABS(IVALUE)
1 FORMAT(I3.3,F5.4)
As I understand it, the IF block and ABS parts should allow this to work for all values on -100 < VALUE < 1000. If I set VALUE = 12.3456, the code above should produce "012.3456" as the output, and it does. However if I have something like VALUE = -12.3456, I'm getting "(3 asterisks).3456" as my output. I know the asterisks usually shows up when there are not enough characters provided for in the FORMAT statement, but 3 should be enough in this example (1 character for the "-" and two characters for "12"). I haven't tested this yet with something like VALUE = -9.876, but I'd expect the output to be "-09.8760".
Is there something wrong in my understanding of how this works? Or is there some other limitation of this technique that I'm violating?
UPDATE: Okay I've looked into this some more, and it seems to be a combination of a negative value and the I3.3 format. If VALUE is positive and I have the I3.3, it will put leading zeros as expected. If VALUE is negative and I only have I3 as my format, I get the correct value output, but it will be padded with spaces before the negative sign instead of padded with zeros after the negative (so -9.8765 is output as " -9.8765", but that leading space breaks what I'm using the .txt file for, so it's not acceptable).
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This uses a set of default rules for how to input and output values of different types (integers, reals, characters, etc.). Often the programmer wants to specify some particular input or output format, e.g., how many decimals places in real numbers. For this purpose Fortran 77 has the format statement.
To pad an integer with leading zeros to a specific length To display the integer as a decimal value, call its ToString(String) method, and pass the string "Dn" as the value of the format parameter, where n represents the minimum length of the string.
Left and Right padding Integer and String in Java You just need to add "%03d" to add 3 leading zeros in an Integer. Formatting instruction to String starts with "%" and 0 is the character which is used in padding. By default left padding is used, 3 is the size and d is used to print integers.
The A format code transfers character data. is an optional width (0 ≤ w) specifying the number of characters to be transferred. If w is not specified, the entire string is transferred. On output, if w is greater than the length of the string, the string is right justified.
Tho problem is with your integer data edit descriptor. With I3.3 you require at least 3 digits and the field width is only 3. There is no place for the minus sign. Use I4.3 or, In Fortran 95 and above, I0.3.
Answer to your edit: Use I0.3, it uses the minimum number of characters necessary.
But finally, you just probably want this: WRITE(*,'(f0.3)') VALUE
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