Stata 15 help for strings


[U] 12.4 Strings


A string is a sequence of characters and is typically enclosed in double quotes. The quotes are not considered a part of the string but delimit the beginning and end of the string. The following are examples of valid strings:

"Hello, world" "String" "string" " string" "string " "" "x/y+3" "1.2"

All the strings above are distinct. Capitalization matters. Leading and trailing spaces matter. Also note that "1.2" is a string and not a number because it is enclosed in quotes.

There is never a circumstance in which a string cannot be delimited with quotes, but there are instances where strings do not have to be delimited by quotes, such as when inputting data. In those cases, nondelimited strings are stripped of their leading and trailing blanks. Delimited strings are always accepted as is.

The special string "", often called null string, is considered by Stata to be a missing. No special meaning is given to the string containing one period, ".".

In addition to double quotes for enclosing strings, Stata also allows compound double quotes: `" and "'. You can type "string" or you can type `"string"', although users seldom type `"string"'. Compound double quotes are of special interest to programmers because they nest and provide a way for a quoted string to itself contain double quotes (either simple or compound). See [U] 18.3.5 Double quotes.

Stata provides two types of strings: str#s and strLs. str#s are fixed-length string storage types. A str36 string can hold 36 characters. Stata allows str1, str2, str3, ..., str2045. strLs are Stata's long strings, which can be up to 2-billion characters long. strLs can hold binary strings, whereas str#s can only hold text characters. See [U] 12.4.7 str1--str2045 and str and [U] 12.4.8 strL for more information. If your strings contain Unicode characters, see [U] 12.4.2 Handling Unicode strings.

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