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`------------------------------------------------------------------
`String Functions from Chapter 8 of Hands on DarkBASIC Pro Volume 1
`------------------------------------------------------------------
`
`remstart ***test area***
cls
print "----Test----"
print
print "Pos(test,s)"
print Pos("test","s")
print
print "Occurs(test,t)"
print Occurs("test","t")
print
print "Insert$(test,er,5)"
print Insert$("test","er",5)
print
print "Delete$(test,2,2)"
print Delete$("test",2,2)
print
print "Replace$(test,T,1)"
print Replace$("test","T",1)
print
print "Copy$(test,2,3)"
print Copy$("test",2,3)
print
print "----Press any key to exit----"
wait key
end
`remend
`=====================================================================
`
`Pos() returns the position of a character in a string
function Pos(s$,c$)
   `*** Result stays at -1 if no match found ***
   Result = -1
   `*** make sure we're looking for a single character ***
   first$ = mid$(c$,1)
   `
   `*** FOR each character in s$ DO ***
   for c = 1 to len(s$)
      `*** IF that character matches what we're after THEN ***
      if mid$(s$,c) = first$
         `*** set Result to this position and exit loop ***
         Result = c
         exit
      endif
   next c
endfunction Result
`
`=====================================================================
`
`Occurs() returns how often a character appears within a string
function Occurs(s$,c$)
   `*** none found so far ***
   Result = 0
   `
   `*** make sure only one caracter ***
   first$ = mid$(c$,1)
   `
   `*** FOR each character in s$ DO ***
   for c = 1 to len(s$)
      `*** IF it matches the required character add 1 to Result***
      if mid$(s$,c) = first$
         Result = Result + 1
      endif
   next c
endfunction Result
`
`=====================================================================
`
`Insert$() inserts one string into another
function Insert$(s1$,s2$,post)
   `*** IF invalid position result$ is original string ***
   if post < 1 or post > len(s1$)+1
      result$ = s1$
   else
      `*** split s1$ into two parts and insert s2$ between them ***
      result$ = left$(s1$,post-1)
      result$ = result$ + s2$
      result$ = result$ + right$(s1$,len(s1$)-(post-1))
   endif
endfunction result$
`
`=====================================================================
`
`Delete$() removes a sections of a string
function Delete$(s$,start,num)
   `*** IF invalid position, result$ is original string ***
   if start < 1 or start > len(s$)
      result$ = s$
   else
      `*** construct result$ from left and right of deleted part ***
      result$ = left$(s$,start-1)
      result$ = result$ + right$(s$,len(s$)-(start+num-1))
   endif
endfunction result$
`
`=====================================================================
`
`Replace$() replaces a single character in a string
function Replace$(s$,c$,post)
   `*** IF invalid position result is original string ***
   if post < 1 or post > len(s$)
      result$ = s$
   else
      `*** make sure only one character is being replaced ***
      first$ = mid$(c$,1)
      `***result is the original string with new character at post***
      result$ = left$(s$,post-1) + first$ + right$(s$,len(s$)-post)
   endif
endfunction result$
`
`=====================================================================
`
`Copy$() returns a copy of part of a string
function Copy$(s$, start, num)
   `***IF invalid position result$ is empty ***
   if start < 1 or start > len(s$)
      result$ = ""
   `*** set # of chars to return to be len(s$) or num ***
   else
      if start + num - 1 > len(s$)
         lastPosition = len(s$)
      else
         lastPosition = start + num - 1
      endif
         for c = start to lastPosition
            result$ = result$ + mid$(s$,c)
         next c
   endif
endfunction result$
`
`=====================================================================