Letter frequency: Difference between revisions

=={{header|S-BASIC}}==

Because S-BASIC lacks an EOF function, some extra care is required to avoid reading beyond the end of file. (CP/M text files are by convention terminated with a Ctrl-Z byte, but not all text editors enforce this if the file would otherwise end on a sector boundary.)

<lang S-BASIC>

$constant EOF = 1AH rem Ctrl-Z signals end of file

rem Convert character to upper case

function upcase(ch = char) = char

if ch >= 'a' and ch <= 'z' then

ch = ch - 32

end = ch

rem Convert string to all upper case characters

function allcaps(source = string) = string

var p = integer

for p = 1 to len(source) do

mid(source,p,1) = upcase(mid(source,p,1))

next p

end = source

rem Preserve console channels (#0 and #1)

files d, d, sa(1)

var ch = char

var i = integer

based errcode = integer

base errcode at 103H rem S-BASIC stores run-time error code here

var filename = string

var total = real

dim real freq(26)

input "Name of text file to process: "; filename

filename = allcaps(filename)

open #2; filename

on error goto 7_trap rem In case input file lacks terminating ^Z

rem Initialize letter counts to zero

for i = 1 to 26

freq(i) = 0

next i

rem Process the file

total = 0

input3 #2; ch

while ch <> EOF do

begin

ch = upcase(ch);

if ch >= "A" and ch <= "Z" then

begin

freq(asc(upcase(ch)) - 64) = freq(asc(upcase(ch)) - 64) + 1

total = total + 1

end

input3 #2; ch

end

goto 8_done rem Jump around error trap

7_trap if errcode <> 15 then

begin

print "Runtime error = ";errcode

goto 9_exit

end

rem otherwise fall through on attempted read past EOF (err = 15)

8_done

close #2

rem Report results

print "Letter Count Percent"

for I = 1 to 26

print chr(i+64);" ";

print using " ##,###"; freq(i);

print using " ##.#"; freq(i) / total * 100

next i

9_exit

end

</lang>

{{out}}

Lincoln's Second Inaugural Address

<pre>

Letter Count Percent

A 101 8.8

B 14 1.2

C 31 2.7

D 59 5.1

E 165 14.3

F 27 2.3

G 28 2.4

H 80 7.0

I 68 5.9

J 0 0.0

K 3 0.3

L 42 3.7

M 13 1.1

N 78 6.8

O 93 8.1

P 15 1.3

Q 1 0.1

R 79 6.9

S 44 3.8

T 126 11.0

U 21 1.8

V 23 2.0

W 28 2.4

X 0 0.0

Y 11 1.0

Z 0 0.0

</pre>