Run-length encoding: Difference between revisions
Content added Content deleted
(→{{header|REXX}}: made incrementing of the DO loop index more idiomatic, changed whitespade and comments, simplified encoding. -- ~~~~) |
m (→decoding: made the DO loop more idiomatic. -- ~~~~) |
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===decoding=== |
===decoding=== |
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<lang rexx>/*REXX program decodes string by using a run-length scheme |
<lang rexx>/*REXX program decodes a string by using a run-length scheme. */ |
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parse arg x |
parse arg x . /*normally, input would be a file*/ |
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if x=='' then x='11WB11W2B23WB13W' /*No input? Then use the default*/ |
if x=='' then x='11WB11W2B23WB13W' /*No input? Then use the default*/ |
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Lx=length(x) /*get the length of the X string.*/ |
Lx=length(x) /*get the length of the X string.*/ |
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y= /*Y is the output string (so far)*/ |
y= /*Y is the output string (so far)*/ |
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do j=1 |
do j=1 by 0 to Lx /*warning! J is modified below.*/ |
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c=substr(x,j,1) |
c=substr(x,j,1) |
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if \datatype(c,'W') then do /*a loner char, simply add to OUT*/ |
if \datatype(c,'W') then do /*a loner char, simply add to OUT*/ |
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y=y || c |
y=y || c; j=j+1; iterate /*j*/ |
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iterate |
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end |
end |
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d=1 |
d=1 |
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do k=j+1 to Lx while datatype(substr(x,k,1),'w') /*look for #end*/ |
do k=j+1 to Lx while datatype(substr(x,k,1),'w') /*look for #end*/ |
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d=d+1 /* |
d=d+1 /*D is the number of digs so far.*/ |
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end /*k*/ |
end /*k*/ |
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n=substr(x,j,d)+1 /*D is length of encoded number.*/ |
n=substr(x,j,d)+1 /*D is length of encoded number.*/ |
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y=y || copies(substr(x,k,1),n) /*N is now the number of chars. */ |
y=y || copies(substr(x,k,1),n) /*N is now the number of chars. */ |
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j=j+d |
j=j+1+d /*increment the DO loop index. */ |
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end /*j*/ |
end /*j*/ |
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