Array: Difference between revisions

===[[SIMPOL]]===

Example: open a text file and compute letter frequency.

<lang simpol>constant iBUFSIZE 500

function main(string filename)

fsfileinputstream fpi

integer e, i, aval, zval, cval

string s, buf, c

array chars

e = 0

fpi =@ fsfileinputstream.new(filename, error=e)

if fpi =@= .nul

s = "Error, file """ + filename + """ not found{d}{a}"

else

chars =@ array.new()

aval = .charval("a")

zval = .charval("z")

i = 1

while i <= 26

chars[i] = 0

i = i + 1

end while

buf = .lcase(fpi.getstring(iBUFSIZE, 1))

while not fpi.endofdata and buf > ""

i = 1

while i <= .len(buf)

c = .substr(buf, i, 1)

cval = .charval(c)

if cval >= aval and cval <= zval

chars[cval - aval + 1] = chars[cval - aval + 1] + 1

end if

i = i + 1

end while

buf = .lcase(fpi.getstring(iBUFSIZE, 1))

end while

s = "Character counts for """ + filename + """{d}{a}"

i = 1

while i <= chars.count()

s = s + .char(aval + i - 1) + ": " + .tostr(chars[i], 10) + "{d}{a}"

i = i + 1

end while

end if

end function s</lang>

As this was being created I realized that in [SIMPOL] I wouldn't have done it this way (in fact, I wrote it differently the first time and had to go back and change it to use an array afterward). In [SIMPOL] we would have used the set object. It acts similarly to a single-dimensional array, but can also use various set operations, such as difference, unite, intersect, etc. One of th einteresting things is that each unique value is stored only once, and the number of duplicates is stored with it. The sample then looks a little cleaner:

<lang simpol>constant iBUFSIZE 500

function main(string filename)

fsfileinputstream fpi

integer e, i, aval, zval

string s, buf, c

set chars

e = 0

fpi =@ fsfileinputstream.new(filename, error=e)

if fpi =@= .nul

s = "Error, file """ + filename + """ not found{d}{a}"

else

chars =@ set.new()

aval = .charval("a")

zval = .charval("z")

buf = .lcase(fpi.getstring(iBUFSIZE, 1))

while not fpi.endofdata and buf > ""

i = 1

while i <= .len(buf)

c = .substr(buf, i, 1)

if .charval(c) >= aval and .charval(c) <= zval

chars.addvalue(c)

end if

i = i + 1

end while

buf = .lcase(fpi.getstring(iBUFSIZE, 1))

end while

s = "Character counts for """ + filename + """{d}{a}"

i = 1

while i <= chars.count()

s = s + chars[i] + ": " + .tostr(chars.valuecount(chars[i]), 10) + "{d}{a}"

i = i + 1

end while

end if

end function s</lang>

The final stage simply reads the totals for each character. One caveat, if a character is unrepresented, then it will not show up at all in this second implementation.