Board index » cppbuilder » How do I do that ? Strings Question.......

2005-12-28 12:10:22 AM
cppbuilder28
Hi all,
I have a given strings that include the words "Green"
and "Blue" in them, and I have to find out (and i don't know
how) if the word "Green" comes before the word "Blue" or after
it, example of 2 strings:
1. " ....Green.....Blue..... "
2. " .....Blue......Green..... "
I know the function strstr() that tells me if the words "Green"
or "Blue" exist in my string, but how do i know who comes first?
I think it should be easy, but i'm not sure.
Thanks! :-)
 

Thanks very much!
 

Thanks very much! great solutions!
 

{smallsort}

"Jonathan Benedicto" < XXXX@XXXXX.COM >wrote:
first.
~ JD
 

Ramy wrote:
AnsiString Str = " ....Green.....Blue..... ";
if( Str.Pos( "Green" ) < Str.Pos( "Blue" ) )
{
// green is first.
}
else
{
// blue is first.
}
If you are using strstr:
char *Str = " ....Green.....Blue..... ";
if( strstr( Str, "Green" ) < strstr( Str, "Blue" ) )
{
// green is first.
}
else
{
// blue is first.
}
HTH
Jonathan
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"Ramy" < XXXX@XXXXX.COM >writes:
char const * blue = strstr(mystring, "Blue");
if (green && blue)
{
bool green_comes_first = (green < blue);
}
else
{
// mystring doesn't contain Green and Blue
}
If you are positive that the string will always contain Blue and
Green, then you can optimize it:
char const * green = strstr(mystring, "Green");
assert(green);
char const * blue = strstr(green, "Blue");
bool green_comes_first = (blue != 0);
This second case continues searching for "Blue" from the point where
it found Green. So if the search fails (blue is null), then you know
that blue came before green. But if blue came after, then the pointer
will be non-zero. I put in the assertion to indicate you either need
to guarantee that Green exists, or you should handle the case where
green is null (and don't use it in the call to find Blue or else
you'll have undefined behavior.)
--
Chris (TeamB);
 

JD wrote:
definite.
Jonathan
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On 27 Dec 2005 09:10:22 -0700, Ramy wrote:
do this.
with AnsiString, use the AnsiPos() function which will give you an int
result.
AnsiString thing1 = "..... blue .... green...";
int bluepos = thing1.AnsiPos("blue");
int greenpos = thing1.AnsiPos("green");
if (bluepos>greenpos)
{
// do something
}
with std::string use find() which will also give you an int
e.g.
std::string thing1 = "..... blue ..... green ...";
int bluepos = thing1.find("blue");
int greenpos = thing1.find("green");
if (bluepos != std::sting::npos && greenpos != std::string::npos &&
bluepos>greenpos)
{
// do something
}
for c-style -- well check out strcspn
--
liz
 

"Ramy" < XXXX@XXXXX.COM >wrote in message
a lower pointer value:
char *message = "This is Blue, this is Green, ...;
char *green = strstr(message, "Green");
char *blue = strstr(message, "Blue");
if( green )
{
if( blue )
{
if( green < blue )
// green comes first
else
// blue comes first
}
else
// green found, but not blue ...
}
else if( blue )
{
// blue found, but not green ...
}
else
// both green and blue not found ...
The only drawback to the above is that the source string is scanned multiple
times. If you remove the strstr() altogether, you can optimize the scanning
to perform a single pass:
char *message = "This is Blue, this is Green, ...;
char *ptr = message;
while( *ptr != '\0' )
{
if( *ptr == 'B' )
{
if( strncmp(ptr, "Blue", 4) == 0 )
{
// blue is first ...
break;
}
}
else if( *ptr == 'G' )
{
if( strncmp(ptr, "Green", 5) == 0 )
{
// green is first ...
break;
}
}
++ptr;
}
Gambit
 

Chris Uzdavinis (TeamB) < XXXX@XXXXX.COM >wrote:
once before "Green" and once after.
- Leo
 

Leo Siefert < XXXX@XXXXX.COM >wrote:
Alan Bellingham
--
ACCU Conference 2006 - 19-22 April, Randolph Hotel, Oxford, UK
 

Leo Siefert < XXXX@XXXXX.COM >writes:
either would be "correct". Just not exclusively correct.
It's an ambiguous situation, and thus a good point to mention. For
unambiguous results, one would have to make the additional guarantee
that Blue and Green both exist once and only once in the string.
--
Chris (TeamB);