| SUB( ) | Substitute Text | 
SUB(string$,search$,replace$[,instance])[,ERR=stmtref])
  
Where:
| instance | Optional. Integer. Which occurrence to find: 
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| search$ | Value for which to search. String expression. Cannot be null. | 
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| replace$ | Text to replace the original search text, if found. String expression. You must include a replace value; however, the value can be null; e.g. sub(A$,B$,"",0,err=100). | 
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| stmtref | Program line number or statement label to which to transfer control. | 
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| string$ | String expression containing the string in which to search-and-replace and perform the substitution. | 
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Converted string.
The SUB( ) function performs a substitution within a string. The search value cannot be null. (That generates an Error #46: Length of string invalid.) If no substitutions occur, no error is generated.
print 'CS';
 list
 A$="Hello there",B$="e",Z$=sub(A$,B$,"",0)
 print Z$+" "+A$
 end
 ->run
Hllo thr Hello there