Snobol 4 ( S tri n g O riented sym bo lic L anguage number 4 ) is the fourth and last occurrence of a number of programming languages for the purpose of manipulating strings . These languages were from 1962 to 1967 in the Bell Laboratories of AT & T by David J. Farber, Ralph E. Griswold developed and Ivan P. Polonsky.
The SNOBOL 4 language supports a number of built-in data types such as integers and floating point numbers, strings, patterns, fields and tables. It also allows the programmer to define additional data types and new functions.
An essential distinguishing feature from the programming languages used at the time is the existence of patterns as a "first-class" data type, i. H. a data type, the value of which can be manipulated in any way like in other programming languages, as well as by operators for chaining and manipulating patterns. Character strings that are generated at runtime can be treated and executed as a program. A pattern in SNOBOL 4 can be very simple, but also very complex. A simple pattern is e.g. B. only a string like "ABCD". A complex pattern, on the other hand, can be a large structure that e.g. B. can describe the complete grammar of a computer language.
In the 1970s and 1980s, SNOBOL 4 was widely used as a language for manipulating text. In recent years, however, its popularity has declined as newer and more efficient languages such as Awk and Perl have become more popular for manipulating strings with regular expressions .