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When an INSPECT statement contains a REPLACING phrase, that statement selectively replaces characters or groups of characters in the designated item.

The REPLACING phrase names a search argument of one or more characters and a condition under which the string can be applied to the item being inspected. Associated with the search argument is the replacement value, which must be the same length as the search argument. Each time the search argument finds a match in the item being inspected, under the condition stated, the replacement value replaces the matched characters.

A BEFORE/AFTER phrase can be used to delimit the area of the item being inspected. A search argument applies only to the delimited area of the item.

5.3.6.1 The Search Argument

The search argument of the REPLACING phrase names a character string and a condition under which the character string should be compared to the delimited string being inspected.

The CHARACTERS form of the search argument specifies that every character in the delimited string being inspected should be considered to match an imaginary character that serves as the search argument. Thus, the replacement value replaces each character in the delimited string. For example:

INSPECT ITEMA REPLACING CHARACTERS ...

The ALL, LEADING, and FIRST forms of the search argument specify a particular character string, which can be represented by a literal or an identifier. The search argument character string can be any length. However, each character of the argument must match a character in the delimited string before the compiler considers the argument matched. For example:

INSPECT ITEMA REPLACING ALL ...

The necessary literal and identifier characteristics are as follows:

• A literal character string must be either nonnumeric or a figurative constant (other than ALL literal). A figurative constant, such as SPACE or ZERO, represents a single character and can be written as " " or "0" with the same effect. Because a figurative constant represents a single character, the replacement value must be one character long.
• An identifier must represent an elementary item of DISPLAY usage. It can be any class. However, if it is not alphabetic, the compiler performs an implicit redefinition of the item. This redefinition is identical to the BEFORE/AFTER delimiter redefinition discussed in Section 5.3.2.

The words ALL, LEADING, and FIRST supply conditions that further delimit the inspection operation:

• ALL specifies that each match the search argument finds in the delimited character string is replaced by the replacement value. When a literal follows the word ALL, it does not have the same meaning as the figurative constant, ALL literal. The figurative constant meaning of ALL "," is a string of consecutive commas, as many as the context of the statement requires. ALL "," as a search argument of the REPLACING phrase means "replace each comma without regard to adjacent characters."
• LEADING specifies that only adjacent matches of the search argument at the leftmost position of the delimited character-string be replaced. At the first failure to match the search argument, the compiler terminates the replacement operation and causes the argument to become inactive.
• FIRST specifies that only the leftmost character string that matches the search argument be replaced. After the replacement operation, the search argument containing this condition becomes inactive.

Whenever the search argument finds a match in the item being inspected, the matched characters are replaced by the replacement value. The word BY followed by an identifier or literal specifies the replacement value. For example:

INSPECT ITEMA REPLACING ALL "A" BY "X" ALL "D" BY "X".

The replacement value must always be the same size as its associated search argument.

If the replacement value is a literal character-string, it must be either a nonnumeric literal or a figurative constant (other than ALL literal). A figurative constant represents as many characters as the length of the search argument requires.

If the replacement value is an identifier, it must be an elementary item of DISPLAY usage. It can be any class. However, if it is not alphanumeric, the compiler conducts an implicit redefinition of the item. This redefinition is the same as the BEFORE/AFTER redefinition discussed in Section 5.3.2.

5.3.6.3 The Replacement Argument

The replacement argument consists of the search argument (with its condition and character-string), the replacement value, and an optional BEFORE/AFTER phrase, as shown in Figure 5-5.

Figure 5-5 The Replacement Argument

One INSPECT...REPLACING statement can contain more than one replacement argument. Several replacement arguments form an argument list, and the manner in which the list is processed affects the action of any given replacement argument.

The following examples show INSPECT statements with replacement argument lists. The text following each one tells how that list will be processed.

INSPECT FIELD1 REPLACING
        ALL "," BY SPACE
        ALL "." BY SPACE
        ALL ";" BY SPACE.

The previous three replacement arguments all have the same replacement value, SPACE, and are active over the entire item being inspected. The statement replaces all commas, periods, and semicolons with space characters and leaves all other characters unchanged.

INSPECT FIELD1 REPLACING
        ALL "0" BY "1"
        ALL "1" BY "0".

Each of these two replacement arguments has its own replacement value and is active over the entire item being inspected. The statement exchanges zeros for 1s and 1s for zeros. It leaves all other characters unchanged.

INSPECT FIELD1 REPLACING
        ALL "0" BY "1" BEFORE SPACE
        ALL "1" BY "0" BEFORE SPACE.

The statement also exchanges zeros and 1s. Here, however, the first space in FIELD1 causes both arguments to become inactive.

INSPECT FIELD1 REPLACING
        ALL "0" BY "1" BEFORE SPACE
        ALL "1" BY "0" BEFORE SPACE
        CHARACTERS BY "*" BEFORE SPACE.

The first space causes the three replacement arguments to become inactive. This argument list exchanges zeros for 1s, 1s for zeros, and asterisks for all other characters in the delimited area. If the BEFORE phrase is removed from the third argument, that argument will remain active across all of FIELD1. Within the area delimited by the first space character, the third argument replaces all characters except 1s and zeros with asterisks. Beyond this area, it replaces all characters (including the space that delimited FIELD1 for the first two arguments, and any zeros and 1s) with asterisks.

5.3.6.5 Interference in Replacement Argument Lists

When several search arguments, all active at the same time, contain one or more identical characters, they can interfere with each other---and consequently affect the replacement operation. This interference is similar to the interference that occurs between tally arguments.

The action of a search argument is never affected by the BEFORE/AFTER delimiters of other arguments, because the compiler scans for delimiter matches before it scans for replacement operations.

The action of a search argument is never affected by the characters of any replacement value, because the scanner does not inspect the replaced characters again during execution of the INSPECT statement. Interference between search arguments, therefore, depends on the order of the arguments, the values of the arguments, and the active/inactive status of the arguments. The discussion in Section 5.3.5.4 about interference in tally argument lists generally applies to replacement arguments as well.

The following rules help minimize interference in replacement argument lists:

1. Place search arguments with LEADING or FIRST conditions at the start of the list.
2. Place any arguments with the CHARACTERS condition at the end of the list.
3. Consider the order of appearance of any search arguments that contain identical characters.