String searching functions
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Jason Buntin
#1 / 7
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 String searching functions The teacher of my programming methodolgy class insists that we use QBASIC to code our solutions to an assignment, and although I know how I want to approach solving it, I am not sure what functions in QBASIC are available that will facilitate my implementation. Here are my *hopefully* simple questions: First, I want to be able to search a string of characters for any
instance of another string, i.e. let's say I want to find out if the
string "and" occurs in the string "jduandhedegf." Are there functions
that are available that will search the string automatically, or do I
need to use LEFT$, MID$, and RIGHT$ along with t{*filter*} non-matching
characters in order to accomplish this?
Second, is there a simple way of reversing a string of characters,
i.e. changing the string "abcd" to "dcba"?!
I appreciate the help. Thank you!
Jason Bunting
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| Sun, 27 Jun 2004 04:33:00 GMT |
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Clif Pen
#2 / 7
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String searching functions On Tue, 8 Jan 2002 13:33:00 -0700, "Jason Bunting" Quote:
>The teacher of my programming methodolgy class insists that we use >QBASIC to code our solutions to an assignment, and although I know how >I want to approach solving it, I am not sure what functions in QBASIC >are available that will facilitate my implementation. Here are my >*hopefully* simple questions: >First, I want to be able to search a string of characters for any
>instance of another string, i.e. let's say I want to find out if the
>string "and" occurs in the string "jduandhedegf." Are there functions
>that are available that will search the string automatically, or do I
>need to use LEFT$, MID$, and RIGHT$ along with t{*filter*} non-matching
>characters in order to accomplish this?
>Second, is there a simple way of reversing a string of characters,
>i.e. changing the string "abcd" to "dcba"?!
>I appreciate the help. Thank you!
>Jason Bunting
' 1. Look up the HELP on INSTR. CLS s$ = "hownowbrowncow" sub$ = "own" p% = INSTR(s$, sub$) PRINT p% 'first location of substring = 2 p% = INSTR(p% + 1, s$, sub$) PRINT p% 'second location of substring = 9 p% = INSTR(p% + 1, s$, sub$) PRINT p% 'substring not in string from this start = 0 ' 2. The easy way is to concatenate the string in reverse order to
' another string variable.
s$ = "abcd"
rev$ = "" 'empty string
FOR ct% = 1 TO LEN(s$)
rev$ = MID$(s$, ct%, 1) + rev$
NEXT ct%
PRINT s$; " reversed is "; rev$
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| Sun, 27 Jun 2004 05:33:37 GMT |
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R.Wiese
#3 / 7
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String searching functions
Hello Jason,
Quote: > The teacher of my programming methodolgy class insists that we use > QBASIC to code our solutions to an assignment, and although I know how > I want to approach solving it, I am not sure what functions in QBASIC > are available that will facilitate my implementation. Here are my > *hopefully* simple questions: > First, I want to be able to search a string of characters for any
> instance of another string, i.e. let's say I want to find out if the
> string "and" occurs in the string "jduandhedegf." Are there functions
> that are available that will search the string automatically, or do I
> need to use LEFT$, MID$, and RIGHT$ along with t{*filter*} non-matching
> characters in order to accomplish this?
You would want to use the INSTR -function. Quote: > Second, is there a simple way of reversing a string of characters,
> i.e. changing the string "abcd" to "dcba"?!
Not by a single instruction. I think you will have to create a Loop that grabs every character of a string and *prepends* it to a Result-string. Can be done in five lines of code (one to initialize the result-string, three for the loop & filling of the result-string, one to copy the result-string back into the origional string). Quote: > I appreciate the help. Thank you!
You're welcome. Regards,
Rudy Wieser
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| Sun, 27 Jun 2004 05:47:39 GMT |
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Thurber Mingu
#4 / 7
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String searching functions
Quote: > On Tue, 8 Jan 2002 13:33:00 -0700, "Jason Bunting"
<snip> Quote: > >First, I want to be able to search a string of characters for any > >instance of another string, i.e. let's say I want to find out if the > >string "and" occurs in the string "jduandhedegf." Are there functions > >that are available that will search the string automatically, or do I > >need to use LEFT$, MID$, and RIGHT$ along with t{*filter*} non-matching > >characters in order to accomplish this? > >Second, is there a simple way of reversing a string of characters,
> >i.e. changing the string "abcd" to "dcba"?!
<snip> Quote: > ' 1. Look up the HELP on INSTR.
Thanks, I found out about that one just after I posted this . . . wouldn't you know it? Quote: > ' 2. The easy way is to concatenate the string in reverse order to
> ' another string variable.
> s$ = "abcd"
> rev$ = "" 'empty string
> FOR ct% = 1 TO LEN(s$)
> rev$ = MID$(s$, ct%, 1) + rev$
> NEXT ct%
> PRINT s$; " reversed is "; rev$
Thank you again, this is beautiful. I was thinking this was the way I would have to accomplish the task, but I was hoping a function was extant for such a purpose . . . Thanks to you, there is now! Thank you for your time! Jason Bunting
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| Sun, 27 Jun 2004 07:19:43 GMT |
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Thurber Mingu
#5 / 7
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String searching functions Rudy, Quote: > > The teacher of my programming methodolgy class insists that we use > > QBASIC to code our solutions to an assignment, and although I know how > > I want to approach solving it, I am not sure what functions in QBASIC > > are available that will facilitate my implementation. Here are my > > *hopefully* simple questions: > > First, I want to be able to search a string of characters for any
> > instance of another string, i.e. let's say I want to find out if the
> > string "and" occurs in the string "jduandhedegf." Are there functions
> > that are available that will search the string automatically, or do I
> > need to use LEFT$, MID$, and RIGHT$ along with t{*filter*} non-matching
> > characters in order to accomplish this?
> You would want to use the INSTR -function.
Thank you! I was perusing the QBASIC help system and found that one after I had posted this question, but I appreciate your help nonetheless! Quote: > > Second, is there a simple way of reversing a string of characters, > > i.e. changing the string "abcd" to "dcba"?! > Not by a single instruction. I think you will have to create a Loop that
> grabs every character of a string and *prepends* it to a Result-string.
Can
> be done in five lines of code (one to initialize the result-string, three
> for the loop & filling of the result-string, one to copy the result-string
> back into the origional string).
This was my fear, not because it would be necessarily difficult, but because I know basic does not offer many string-manipulation functions. Thank you for the time and effort! Jason Bunting
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| Sun, 27 Jun 2004 07:22:55 GMT |
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Andreas Meil
#6 / 7
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String searching functions
Quote: > First, I want to be able to search a string of characters for any
> instance of another string, i.e. let's say I want to find out if the
> string "and" occurs in the string "jduandhedegf." Are there functions
> that are available that will search the string automatically, or do I
> need to use LEFT$, MID$, and RIGHT$ along with t{*filter*} non-matching
> characters in order to accomplish this?
Yes, use INSTR(): INSTR("jduandhedegf.", "and")
returns 4 (MID$ position), i.e. exactly what you want. Note: 0 = no
occurence.
Quote: > Second, is there a simple way of reversing a string of characters,
> i.e. changing the string "abcd" to "dcba"?!
There's no built-in function, but you can easily write FUNCTION Reverse$(t$)
h$ = ""
FOR i% = 1 TO LEN(t$)
h$ = MID$(t$, i%, 1) + h$
NEXT i%
Reverse$ = h$
END FUNCTION
=> PRINT Reverse$("abcd")
returns "dcba" as expected.
Andreas
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| Mon, 28 Jun 2004 04:15:48 GMT |
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Thurber Mingu
#7 / 7
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String searching functions
Quote:
> > First, I want to be able to search a string of characters for any > > instance of another string, i.e. let's say I want to find out if the > > string "and" occurs in the string "jduandhedegf." Are there functions > > that are available that will search the string automatically, or do I > > need to use LEFT$, MID$, and RIGHT$ along with t{*filter*} non-matching > > characters in order to accomplish this? > Yes, use INSTR():
> INSTR("jduandhedegf.", "and")
> returns 4 (MID$ position), i.e. exactly what you want. Note: 0 = no
> occurence.
> > Second, is there a simple way of reversing a string of characters,
> > i.e. changing the string "abcd" to "dcba"?!
> There's no built-in function, but you can easily write
> FUNCTION Reverse$(t$)
> h$ = ""
> FOR i% = 1 TO LEN(t$)
> h$ = MID$(t$, i%, 1) + h$
> NEXT i%
> Reverse$ = h$
> END FUNCTION
> => PRINT Reverse$("abcd")
> returns "dcba" as expected.
Thank you for the time you took answering my questions! Jason Bunting
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| Mon, 28 Jun 2004 09:55:10 GMT |
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