String Instructions — CONCAT, FIND, MID, INSERT, DELETE

A STRING tag holds text: up to 82 characters, with LEN saying how many are in use. These five instructions build text and take it apart. Use them to put an operator message together from pieces, to find a separator in a barcode, or to pull a part number out of a longer code.

Each one runs on every scan its rung is true, and does nothing on a false rung. Each one writes its result into its last operand. That operand may also be one it reads: CONCAT(Msg,Suffix,Msg) adds Suffix to the end of Msg.

Characters are counted from 1: in 'hello', h is character 1 and o is character 5.

CONCAT — Join Two STRINGsCopy Anchor Link

Joins two STRINGs, Source A then Source B, into the destination STRING.

With AlarmPrefix holding 'ALARM: ' and AlarmText holding 'Low oil', DisplayLine becomes 'ALARM: Low oil'. If the two hold more than 82 characters together, the result keeps the first 82 and Studio shows a warning.

FIND — Find Text in a STRINGCopy Anchor Link

Finds where the Search STRING first appears in the Source STRING, from the Start character on, and stores its position.

With Barcode holding 'AB-123' and Separator holding '-', SeparatorAt becomes 3. When the text is not there, the result is 0. Upper and lower case are different characters, so searching 'hello' for 'H' finds nothing.

start says where the search begins, and it must be a character the source has: 1 to its LEN. Outside that, the result is 0 and Studio shows a warning. A typed-in start of 0 is refused before the program runs.

MID — Take Part of a STRINGCopy Anchor Link

Copies Qty characters of the Source STRING, from the Start character on, into the destination STRING.

qty comes before start. MID(Barcode,3,4,PartNumber) takes three characters, starting at character 4:

With Barcode holding 'AB-123', PartNumber becomes '123'. If qty runs past the end of the source, MID takes the rest and Studio shows a warning. If start is not a character the source has, dest is left as it was.

INSERT — Put Text Into a STRINGCopy Anchor Link

Puts the Source B STRING into the Source A STRING at the Start character and stores the result in the destination STRING.

With Reading holding '25.5' and Unit holding ' C', Shown becomes '25.5 C'. The text goes in before the start character, so start may be 1 to one past the end of sourceA, and one past the end adds it after the last character. If the result would be longer than 82 characters, dest is left as it was and Studio shows a warning.

DELETE — Take Text Out of a STRINGCopy Anchor Link

Removes Qty characters of the Source STRING, from the Start character on, and stores the rest in the destination STRING.

Like MID, qty comes before start:

With Barcode holding 'AB-123', Suffix becomes '123': the first three characters are removed. If qty runs past the end, everything from start on is removed and Studio shows a warning.

A STRING with a broken LENCopy Anchor Link

LEN can be set on its own, to a number outside 0 to 82. A string instruction never reads such a STRING. It leaves dest as it was, or stores 0 for FIND, and Studio shows a warning that names the STRING.

Common MistakesCopy Anchor Link

• Putting text in quotes into a string instruction, such as CONCAT(Msg,' C',Msg). Put the text in a STRING tag and use the tag. Text in quotes goes only in MOVE and the compare instructions.
• Swapping qty and start in MID and DELETE. qty comes first.
• Typing a qty or a start with a decimal point, such as 1.0. They take whole numbers only, so type 1.
• Counting characters from 0. The first character is 1.

RelatedCopy Anchor Link

• MOVE — copy text into a STRING
• Compare — compare two STRINGs
• String conversion — numbers to text and back, and letter case
• String instructions in Structured Text