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Join Date: Apr 2008
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I want to split data in a string. The string will consist of several data. Before every element the length ofthe element will come. I want to exract data one by one.
e.g. char * abc = "[length ]acsfdnhsjg[len]gvsdgdvheg[len]efgwetrge";
can someone help me!!!!!!!
e.g. char * abc = "[length ]acsfdnhsjg[len]gvsdgdvheg[len]efgwetrge";
can someone help me!!!!!!!
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Join Date: May 2007
Location: Ireland
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So it'll say like 13 and you want to grab the next 13 characters? Will the length actually be wrapped in []? If ya have boost installed use boost::regex for the simplest way. You might be able to use strtok to split them all with respect to [, skip till ] and grab the rest of the string. If [ and ] mark the size of the string you don't actually need the length.
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Join Date: Apr 2008
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no its not warapped in {}. just for understanding I used it. so i couldnt use strtok either.
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example for the format of the data is:
5gterfs2rt5tyuri4oiuy10rtyuioiuyt
5gterfs2rt5tyuri4oiuy10rtyuioiuyt
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Join Date: May 2008
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Posting Whiz
Probably easiest would be to read the length and then extract the characters after it one by one. The code is longer because Ed put in complete error checking:
Error checking is good. It's because of the error checking that Edward found an error in your sample string. The first data set doesn't match the length you gave "5gterfs". "gterfs" has 6 characters but the length only specifies 5. 
#include <cctype>
#include <cstdlib>
#include <iostream>
int main()
{
char *p = "6gterfs2rt5tyuri4oiuy10rtyuioiuyt";
char *data = p;
long length;
while (*data != '\0') {
// Save the current position for error checking
char *temp = data;
long length = std::strtol(data, &data, 0);
// Make sure a leading length is present
if (data == temp) {
std::cerr << "Invalid length detected "
"at [" << data << "]\n";
break;
}
// Make sure trailing data is present
if (*data == '\0') {
std::cerr << "Length detected ["
<< length << "] without data\n";
break;
}
for (long i = 0; *data != '\0' && i < length; ++i)
std::cout << *data++;
std::cout << '\n';
// Make sure the data matches the length
if (*data != '\0' && !std::isdigit(*data)) {
std::cerr << "Bad length [" << length
<< "] before [" << data << "]\n";
break;
}
}
} Last edited by Radical Edward : May 29th, 2008 at 8:33 am.
If at first you don't succeed, keep on sucking until you do succeed.
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thanks edward.
The solution given by the Edward is woring fine. but it fails if data starts with a digit.
e.g. char *p = "006gterfs002rt005tyuri0028ab004oiuy010rtyuioiuyt";
here length of the data = 002 and data =8ab
and the other thing is here data will be display character by character.
I want to assigned the extracted data into a char pointer.
e.g. char * ptr;
and ptr = ab
The solution given by the Edward is woring fine. but it fails if data starts with a digit.
e.g. char *p = "006gterfs002rt005tyuri0028ab004oiuy010rtyuioiuyt";
here length of the data = 002 and data =8ab
and the other thing is here data will be display character by character.
I want to assigned the extracted data into a char pointer.
e.g. char * ptr;
and ptr = ab
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Join Date: May 2008
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Posting Whiz
> but it fails if data starts with a digit.
With the example you gave before: "5gterfs2rt5tyuri4oiuy10rtyuioiuyt", that's an impossible case because the length could be multiple digits. Your new example suggests that the length is a fixed width number of 3 digits with leading zeros. That's different, and it's a good way to see how minor differences in the format can change the suitability of a solution. When you need help parsing a string, it's best to provide a formal specification and at least some of the actual data rather than a summary.
> here length of the data = 002 and data =8ab
That's still a logical error though. The length is 2, but the number of data characters is 3. Here's another example that extracts the data--without error checking!--using a 3 digit length:
>and the other thing is here data will be display character by character.
How you process the characters after they're extracted is your business, not Ed's. The code was meant to be an example of how to extract the characters, not a complete solution to your problem.
With the example you gave before: "5gterfs2rt5tyuri4oiuy10rtyuioiuyt", that's an impossible case because the length could be multiple digits. Your new example suggests that the length is a fixed width number of 3 digits with leading zeros. That's different, and it's a good way to see how minor differences in the format can change the suitability of a solution.
When you need help parsing a string, it's best to provide a formal specification and at least some of the actual data rather than a summary.> here length of the data = 002 and data =8ab
That's still a logical error though. The length is 2, but the number of data characters is 3. Here's another example that extracts the data--without error checking!--using a 3 digit length:
#include <cstdio>
#include <cstdlib>
#include <iostream>
int main()
{
char *p = "006gterfs002rt005tyuri0038ab004oiuy010rtyuioiuyt";
char *data = p;
while (*data != '\0') {
char temp[4];
int length;
sscanf(data, "%3[0123456789]", temp);
length = std::strtol(temp, 0, 10);
data += 3;
for (int i = 0; *data != '\0' && i < length; ++i)
std::cout << *data++;
std::cout << '\n';
}
}How you process the characters after they're extracted is your business, not Ed's. The code was meant to be an example of how to extract the characters, not a complete solution to your problem.
If at first you don't succeed, keep on sucking until you do succeed.
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