Output editing refers to formatting output values by suppressing leading zeros and adding special characters—such as decimal radix characters, thousands separators, and currency symbols—to make the values easier for people looking at the output to comprehend
Editor's Note: This article is excerpted from chapter 3 of Programming in ILE RPG, Fifth Edition.
Output editing refers to formatting output values by suppressing leading zeros and adding special characters—such as decimal radix characters, thousands separators, and currency symbols—to make the values easier for people looking at the output to comprehend. RPG and DDS allow you to edit numeric fields (but not character fields). Editing is used in part because of the way numbers are stored in the computer. For example, if Amount, a six-byte field with two decimal positions, is assigned the value 31.24, the computer stores that value as 003124. Although the computer keeps track of the decimal position, a radix character is not actually stored as part of the numeric value. If you print Amount without editing, the number prints as 003124—the nonsignificant zeros appears, and there is no indication of where the decimal should be.
To make it easier to specify the most commonly desired kinds of editing, DDS includes several built-in edit codes you can use to indicate how you want to print a field’s value. You associate an edit code with a field by entering the code in parentheses immediately following the EDTCDE keyword at the field level for each field you want to edit. All commonly used edit codes automatically result in zero suppression (i.e., printing blanks in place of nonsignificant leading zeros) because that is a standard desired format.
Some editing decisions vary with the application. Do you want numbers to print with thousands separators (e.g., commas) inserted? How do you want to handle negative values— ignore them and omit any sign, print CR immediately after a negative value, print a minus sign (-) after the value, or print a floating negative sign to the left of the value? And when a field has a value of zero, do you want to print zeros or leave that spot on the report blank? A set of 16 edit codes (1 through 4, A through D, and J through Q) cover all combinations of these three options. The table in Figure 1 details the effects of the 16 edit codes. Thus, if you want commas, zero balances to print, and a floating negative sign, you use edit code N. If you do not want commas or a sign but do want zero balances to print, use edit code 3.
Figure 3.12: Edit codes
DDS provides four additional useful edit codes: W, X, Y, and Z. Edit codes W and Y result in slashes being printed as part of a number representing a date. Using edit code Y renders the value 12252015 as 12/25/2015, and the value 122515 prints as 12/25/15. Edit code W prints 20151225 as 2015/12/25, and 151225 displays as 15/12/25. Although edit codes W and Y are normally used to edit dates, you can also use them with any field for which slash insertion is appropriate.
Edit code Z simply zero-suppresses leading nonsignificant zeros. Z does not enable the printing of a decimal point or a negative sign. So if a field contains a value of -234.56, the Z edit code causes the field to print as 23456. The use of Z is usually limited to whole number fields.
With one exception, all the edit codes suppress leading zeros. Edit code X, however, retains them. For this reason, the X edit code is useful when you want to convert a numeric value to a character string and retain the leading zeros.
You can include a floating currency symbol immediately to the left of a numeric value if you are using an edit code (except for W–Z). For example, specifying EDTCDE(J '$') prints a number as $12,345.67. Or, you can specify asterisk fill to print an asterisk in place of each suppressed zero; for example, EDTCDE(J *) might print ***12,345.67.
Given the variety of edit codes built into DDS, you might expect find a code to fit your every need. Unfortunately, that is not the case. Telephone numbers and tax identification numbers represent good examples of values that we are used to seeing in a format that an edit code cannot supply. DDS includes an alternative to edit codes, called edit words, which can help in this kind of situation.
You code an edit word (EDTWRD) in the Functions area of the DDS at the field level for the field you want to edit. Edit words and edit codes are never used together for the same field because they perform the same function. An edit word supplies a template, or mask, into which you insert a number, and you enclose the template with apostrophes. Within the template, a blank position indicates where a digit should appear, and a 0 indicates where zero suppression should occur. With no zero in the edit word, the default is to zero suppress to the first significant digit.
You can use any characters as insertion characters within the template. The insertion characters print in the specified place, provided they are to the right of a significant digit. A currency symbol at the left of the edit word signals a fixed currency symbol, and a currency symbol adjacent to a zero denotes a floating currency symbol. To indicate a blank as an insertion character, use an ampersand (&).
Examine the following table to see how edit words work. You can duplicate the effects of edit codes with an edit word. Generally, RPG programmers use edit words only when no edit code is available that provides the format they want for their output.