Why was semi-colon chosen to end a statement?

Question

Was it because while typing, semi-colon appears under little finger when hands are positioned in default position to say - with index finger on F and J?

Or is there anything more substantial?

Answer 1

The use of semicolon as a statement separator / terminator goes back at least to Algol-60.

I think that the most likely reason was that the dot character was already used as a decimal point in floating-point literals, and colon was used in the assignment operator (:=). So that left semicolon as the next most obvious punctuation character available.

Note:

• Earlier dialects of Algol used ' as the statement terminator,
• COBOL used .,
• FORTRAN didn't need a statement terminator at all because it didn't allow multiple statements on one line.

Many languages of that era were designed for 6 or even 5 bit character sets, which seriously constrained the language designers' options. As an undergraduate, I remember that we couldn't use IBM 026 keypunches for Pascal, because they couldn't cope with curly brackets, etcetera in string literals. We had to queue for the 029 keypunches.

In those days, typing efficiency wasn't a major concern. Typical input devices from the 1950's and 1960's era were too "clunky" for touch typing. And a lot of programs were written out on coding pads, and then keyed in by keypunch operators.

Answer 2

I think it was because almost all the symbols in the historical keyboards were used up as operators with one remaining which could possibly be the semicolon.