Concatenating Numbers
A number can be concatenated to another number using the concatenate operator (_). InterSystems IRIS first converts each number to its canonical form, then performs a string concatenation on the results. Thus, the following all result in 1234: 12_34, 12_+34, 12_--34, 12.0_34, 12_0034.0, 12E0_34. The concatenation 12._34 results in 1234, but the concatenation 12_.34 results in 12.34. The concatenation 12_-34 results in the string “12-34”.
InterSystems IRIS performs numeric concatenation and arithmetic operations on numbers after converting those numbers to canonical form. It performs these operations in strict left-to-right order, unless you specify parentheses to prioritize an operation. The following example explains one consequence of this:
WRITE 7_-6+5 // returns 12
In this example, the concatenation returns the string “7-6”. This, of course, is not a canonical number. InterSystems IRIS converts this string to a canonical number by truncating at the first non-numeric character (the embedded minus sign). It then performs the next operation using this canonical number 7 + 5 = 12.
