C++ : Interpret unicode white space
I have a file which contains text (ASCII + unicode) and I am trying to count total words in it using a C++ program. It is a requirement that I should read the file line by line (using getline) and then process each line to count the words within it.
So I have written the following simple program:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
int main(int argc, char* argv) {
uint64_t ct = 0;
std::string line;
std::ifstream infile(argv[1]);
while(std::getline(infile, line)) {
std::stringstream inputStream(line);
std::string token;
while (inputStream >> token) {
++ct;
}
}
std::cout << ct << std::endl;
return 0;
}
However, the above program outputs a number that is lesser than what wc -w command gives. To narrow down the problem, I modified the program to simply output whatever it reads. So now the program becomes:
int main(int argc, char* argv) {
uint64_t ct = 0;
std::string line;
std::ifstream infile(argv[1]);
while(std::getline(infile, line)) {
std::stringstream inputStream(line);
std::string token;
while (inputStream >> token) {
std::cout << token << " ";
}
std::cout << std::endl;
}
return 0;
}
I redirected the output of this program to another file. Now, when I run wc -w on this new file, the number is same as running wc -w on the original file. This means, I am reading all the words (i.e., "words" defined by wc) in my program. And hence, a reasonable explanation would be that one of the values of token that is read using inputStream >> token consists of some unicode character that is interpreted as a white space by wc program. So how do I change my program to also support such interpretation of unicode white space characters?
c++ string unicode
asked Jun 28 '17 at 23:27
John ElaineJohn Elaine
12413
|
show 2 more comments
I have a file which contains text (ASCII + unicode) and I am trying to count total words in it using a C++ program. It is a requirement that I should read the file line by line (using getline) and then process each line to count the words within it.
So I have written the following simple program:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
int main(int argc, char* argv) {
uint64_t ct = 0;
std::string line;
std::ifstream infile(argv[1]);
while(std::getline(infile, line)) {
std::stringstream inputStream(line);
std::string token;
while (inputStream >> token) {
++ct;
}
}
std::cout << ct << std::endl;
return 0;
}
However, the above program outputs a number that is lesser than what wc -w command gives. To narrow down the problem, I modified the program to simply output whatever it reads. So now the program becomes:
int main(int argc, char* argv) {
uint64_t ct = 0;
std::string line;
std::ifstream infile(argv[1]);
while(std::getline(infile, line)) {
std::stringstream inputStream(line);
std::string token;
while (inputStream >> token) {
std::cout << token << " ";
}
std::cout << std::endl;
}
return 0;
}
I redirected the output of this program to another file. Now, when I run wc -w on this new file, the number is same as running wc -w on the original file. This means, I am reading all the words (i.e., "words" defined by wc) in my program. And hence, a reasonable explanation would be that one of the values of token that is read using inputStream >> token consists of some unicode character that is interpreted as a white space by wc program. So how do I change my program to also support such interpretation of unicode white space characters?
c++ string unicode
asked Jun 28 '17 at 23:27
John ElaineJohn Elaine
12413
1
That's not going to be easy without external dependencies. Boost implements this as a lookup table to map each character to a given type, and then checks the type with some heuristics. Basically, you either need decent Unicode support, like Boost or Qt, or don't bother. boost.org/doc/libs/1_62_0/boost/spirit/home/support/…
– Alexander Huszagh
Jun 28 '17 at 23:30
If you are interested, the relevant task would be to convert your Unicode text to UTF-32 (check if a start byte or a continuation byte, or plain ASCII), check the code point to see if it is whitespace using a lookup table, and then use it as a token. If that sounds involved, and a lot of work, it is, and there are many libraries that already do this for you. Boost notably is one.
– Alexander Huszagh
Jun 28 '17 at 23:34
2
There are quite a few "Space" characters in Unicode - so this becomes a map of characters and lookups. Error prone to because of the need to test against all the fun that can come through. I will say, from a high level, that C++ may not be the best language for string manipulations like this.
– Michael Dorgan
Jun 28 '17 at 23:36
@AlexanderHuszagh: I see. I can use boost for this task. What would be the best way to tokenize a string using boost? Doing that would be easier than usingisspacecheck for each character.
– John Elaine
Jun 28 '17 at 23:53
@JohnElaine What's your source encoding, and can you convert to UTF-32? Checking for whitespace is easiest in UTF-32. Basically, I would get line-by-line, convert to UTF-32, iterate code point by code point and check if each is whitespace and process token-by-token. It's not pretty, but it can be pretty easy to do. If you do not want to convert to UTF-32, you could look character by character in UTF-8: if it's an ASCII character (< 128), check against known ASCII space characters, otherwise, fill to a uint32_t.
– Alexander Huszagh
Jun 29 '17 at 0:03
|
show 2 more comments
I have a file which contains text (ASCII + unicode) and I am trying to count total words in it using a C++ program. It is a requirement that I should read the file line by line (using getline) and then process each line to count the words within it.
So I have written the following simple program:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
int main(int argc, char* argv) {
uint64_t ct = 0;
std::string line;
std::ifstream infile(argv[1]);
while(std::getline(infile, line)) {
std::stringstream inputStream(line);
std::string token;
while (inputStream >> token) {
++ct;
}
}
std::cout << ct << std::endl;
return 0;
}
However, the above program outputs a number that is lesser than what wc -w command gives. To narrow down the problem, I modified the program to simply output whatever it reads. So now the program becomes:
int main(int argc, char* argv) {
uint64_t ct = 0;
std::string line;
std::ifstream infile(argv[1]);
while(std::getline(infile, line)) {
std::stringstream inputStream(line);
std::string token;
while (inputStream >> token) {
std::cout << token << " ";
}
std::cout << std::endl;
}
return 0;
}
I redirected the output of this program to another file. Now, when I run wc -w on this new file, the number is same as running wc -w on the original file. This means, I am reading all the words (i.e., "words" defined by wc) in my program. And hence, a reasonable explanation would be that one of the values of token that is read using inputStream >> token consists of some unicode character that is interpreted as a white space by wc program. So how do I change my program to also support such interpretation of unicode white space characters?
c++ string unicode
asked Jun 28 '17 at 23:27
John ElaineJohn Elaine
12413
I have a file which contains text (ASCII + unicode) and I am trying to count total words in it using a C++ program. It is a requirement that I should read the file line by line (using getline) and then process each line to count the words within it.
So I have written the following simple program:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
int main(int argc, char* argv) {
uint64_t ct = 0;
std::string line;
std::ifstream infile(argv[1]);
while(std::getline(infile, line)) {
std::stringstream inputStream(line);
std::string token;
while (inputStream >> token) {
++ct;
}
}
std::cout << ct << std::endl;
return 0;
}
However, the above program outputs a number that is lesser than what wc -w command gives. To narrow down the problem, I modified the program to simply output whatever it reads. So now the program becomes:
int main(int argc, char* argv) {
uint64_t ct = 0;
std::string line;
std::ifstream infile(argv[1]);
while(std::getline(infile, line)) {
std::stringstream inputStream(line);
std::string token;
while (inputStream >> token) {
std::cout << token << " ";
}
std::cout << std::endl;
}
return 0;
}
I redirected the output of this program to another file. Now, when I run wc -w on this new file, the number is same as running wc -w on the original file. This means, I am reading all the words (i.e., "words" defined by wc) in my program. And hence, a reasonable explanation would be that one of the values of token that is read using inputStream >> token consists of some unicode character that is interpreted as a white space by wc program. So how do I change my program to also support such interpretation of unicode white space characters?
c++ string unicode
c++ string unicode
asked Jun 28 '17 at 23:27
John ElaineJohn Elaine
12413
asked Jun 28 '17 at 23:27
John ElaineJohn Elaine
12413
asked Jun 28 '17 at 23:27
John ElaineJohn Elaine
12413
asked Jun 28 '17 at 23:27
John ElaineJohn Elaine
12413
asked Jun 28 '17 at 23:27
John ElaineJohn Elaine
12413
12413
1
That's not going to be easy without external dependencies. Boost implements this as a lookup table to map each character to a given type, and then checks the type with some heuristics. Basically, you either need decent Unicode support, like Boost or Qt, or don't bother. boost.org/doc/libs/1_62_0/boost/spirit/home/support/…
– Alexander Huszagh
Jun 28 '17 at 23:30
If you are interested, the relevant task would be to convert your Unicode text to UTF-32 (check if a start byte or a continuation byte, or plain ASCII), check the code point to see if it is whitespace using a lookup table, and then use it as a token. If that sounds involved, and a lot of work, it is, and there are many libraries that already do this for you. Boost notably is one.
– Alexander Huszagh
Jun 28 '17 at 23:34
2
There are quite a few "Space" characters in Unicode - so this becomes a map of characters and lookups. Error prone to because of the need to test against all the fun that can come through. I will say, from a high level, that C++ may not be the best language for string manipulations like this.
– Michael Dorgan
Jun 28 '17 at 23:36
@AlexanderHuszagh: I see. I can use boost for this task. What would be the best way to tokenize a string using boost? Doing that would be easier than usingisspacecheck for each character.
– John Elaine
Jun 28 '17 at 23:53
@JohnElaine What's your source encoding, and can you convert to UTF-32? Checking for whitespace is easiest in UTF-32. Basically, I would get line-by-line, convert to UTF-32, iterate code point by code point and check if each is whitespace and process token-by-token. It's not pretty, but it can be pretty easy to do. If you do not want to convert to UTF-32, you could look character by character in UTF-8: if it's an ASCII character (< 128), check against known ASCII space characters, otherwise, fill to a uint32_t.
– Alexander Huszagh
Jun 29 '17 at 0:03
|
show 2 more comments
1
That's not going to be easy without external dependencies. Boost implements this as a lookup table to map each character to a given type, and then checks the type with some heuristics. Basically, you either need decent Unicode support, like Boost or Qt, or don't bother. boost.org/doc/libs/1_62_0/boost/spirit/home/support/…
– Alexander Huszagh
Jun 28 '17 at 23:30
If you are interested, the relevant task would be to convert your Unicode text to UTF-32 (check if a start byte or a continuation byte, or plain ASCII), check the code point to see if it is whitespace using a lookup table, and then use it as a token. If that sounds involved, and a lot of work, it is, and there are many libraries that already do this for you. Boost notably is one.
– Alexander Huszagh
Jun 28 '17 at 23:34
2
There are quite a few "Space" characters in Unicode - so this becomes a map of characters and lookups. Error prone to because of the need to test against all the fun that can come through. I will say, from a high level, that C++ may not be the best language for string manipulations like this.
– Michael Dorgan
Jun 28 '17 at 23:36
@AlexanderHuszagh: I see. I can use boost for this task. What would be the best way to tokenize a string using boost? Doing that would be easier than usingisspacecheck for each character.
– John Elaine
Jun 28 '17 at 23:53
@JohnElaine What's your source encoding, and can you convert to UTF-32? Checking for whitespace is easiest in UTF-32. Basically, I would get line-by-line, convert to UTF-32, iterate code point by code point and check if each is whitespace and process token-by-token. It's not pretty, but it can be pretty easy to do. If you do not want to convert to UTF-32, you could look character by character in UTF-8: if it's an ASCII character (< 128), check against known ASCII space characters, otherwise, fill to a uint32_t.
– Alexander Huszagh
Jun 29 '17 at 0:03
1
1
That's not going to be easy without external dependencies. Boost implements this as a lookup table to map each character to a given type, and then checks the type with some heuristics. Basically, you either need decent Unicode support, like Boost or Qt, or don't bother. boost.org/doc/libs/1_62_0/boost/spirit/home/support/…
– Alexander Huszagh
Jun 28 '17 at 23:30
That's not going to be easy without external dependencies. Boost implements this as a lookup table to map each character to a given type, and then checks the type with some heuristics. Basically, you either need decent Unicode support, like Boost or Qt, or don't bother. boost.org/doc/libs/1_62_0/boost/spirit/home/support/…
– Alexander Huszagh
Jun 28 '17 at 23:30
If you are interested, the relevant task would be to convert your Unicode text to UTF-32 (check if a start byte or a continuation byte, or plain ASCII), check the code point to see if it is whitespace using a lookup table, and then use it as a token. If that sounds involved, and a lot of work, it is, and there are many libraries that already do this for you. Boost notably is one.
– Alexander Huszagh
Jun 28 '17 at 23:34
If you are interested, the relevant task would be to convert your Unicode text to UTF-32 (check if a start byte or a continuation byte, or plain ASCII), check the code point to see if it is whitespace using a lookup table, and then use it as a token. If that sounds involved, and a lot of work, it is, and there are many libraries that already do this for you. Boost notably is one.
– Alexander Huszagh
Jun 28 '17 at 23:34
2
2
There are quite a few "Space" characters in Unicode - so this becomes a map of characters and lookups. Error prone to because of the need to test against all the fun that can come through. I will say, from a high level, that C++ may not be the best language for string manipulations like this.
– Michael Dorgan
Jun 28 '17 at 23:36
There are quite a few "Space" characters in Unicode - so this becomes a map of characters and lookups. Error prone to because of the need to test against all the fun that can come through. I will say, from a high level, that C++ may not be the best language for string manipulations like this.
– Michael Dorgan
Jun 28 '17 at 23:36
@AlexanderHuszagh: I see. I can use boost for this task. What would be the best way to tokenize a string using boost? Doing that would be easier than using
isspace check for each character.– John Elaine
Jun 28 '17 at 23:53
@AlexanderHuszagh: I see. I can use boost for this task. What would be the best way to tokenize a string using boost? Doing that would be easier than using
isspace check for each character.– John Elaine
Jun 28 '17 at 23:53
@JohnElaine What's your source encoding, and can you convert to UTF-32? Checking for whitespace is easiest in UTF-32. Basically, I would get line-by-line, convert to UTF-32, iterate code point by code point and check if each is whitespace and process token-by-token. It's not pretty, but it can be pretty easy to do. If you do not want to convert to UTF-32, you could look character by character in UTF-8: if it's an ASCII character (< 128), check against known ASCII space characters, otherwise, fill to a uint32_t.
– Alexander Huszagh
Jun 29 '17 at 0:03
@JohnElaine What's your source encoding, and can you convert to UTF-32? Checking for whitespace is easiest in UTF-32. Basically, I would get line-by-line, convert to UTF-32, iterate code point by code point and check if each is whitespace and process token-by-token. It's not pretty, but it can be pretty easy to do. If you do not want to convert to UTF-32, you could look character by character in UTF-8: if it's an ASCII character (< 128), check against known ASCII space characters, otherwise, fill to a uint32_t.
– Alexander Huszagh
Jun 29 '17 at 0:03
|
show 2 more comments
1 Answer
1
active
oldest
votes
You can go by either:
A. Java's definition of Unicode (not non-breaking) whitespace.
or
B. Wikipedia's list of all 25 Unicode code points defined as whitespace.
answered Nov 26 '18 at 19:49
veganaiZeveganaiZe
313112
add a comment |
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1 Answer
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You can go by either:
A. Java's definition of Unicode (not non-breaking) whitespace.
or
B. Wikipedia's list of all 25 Unicode code points defined as whitespace.
answered Nov 26 '18 at 19:49
veganaiZeveganaiZe
313112
add a comment |
You can go by either:
A. Java's definition of Unicode (not non-breaking) whitespace.
or
B. Wikipedia's list of all 25 Unicode code points defined as whitespace.
answered Nov 26 '18 at 19:49
veganaiZeveganaiZe
313112
add a comment |
You can go by either:
A. Java's definition of Unicode (not non-breaking) whitespace.
or
B. Wikipedia's list of all 25 Unicode code points defined as whitespace.
answered Nov 26 '18 at 19:49
veganaiZeveganaiZe
313112
You can go by either:
A. Java's definition of Unicode (not non-breaking) whitespace.
or
B. Wikipedia's list of all 25 Unicode code points defined as whitespace.
answered Nov 26 '18 at 19:49
veganaiZeveganaiZe
313112
answered Nov 26 '18 at 19:49
veganaiZeveganaiZe
313112
answered Nov 26 '18 at 19:49
veganaiZeveganaiZe
313112
answered Nov 26 '18 at 19:49
veganaiZeveganaiZe
313112
313112
add a comment |
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1
That's not going to be easy without external dependencies. Boost implements this as a lookup table to map each character to a given type, and then checks the type with some heuristics. Basically, you either need decent Unicode support, like Boost or Qt, or don't bother. boost.org/doc/libs/1_62_0/boost/spirit/home/support/…
– Alexander Huszagh
Jun 28 '17 at 23:30
If you are interested, the relevant task would be to convert your Unicode text to UTF-32 (check if a start byte or a continuation byte, or plain ASCII), check the code point to see if it is whitespace using a lookup table, and then use it as a token. If that sounds involved, and a lot of work, it is, and there are many libraries that already do this for you. Boost notably is one.
– Alexander Huszagh
Jun 28 '17 at 23:34
2
There are quite a few "Space" characters in Unicode - so this becomes a map of characters and lookups. Error prone to because of the need to test against all the fun that can come through. I will say, from a high level, that C++ may not be the best language for string manipulations like this.
– Michael Dorgan
Jun 28 '17 at 23:36
@AlexanderHuszagh: I see. I can use boost for this task. What would be the best way to tokenize a string using boost? Doing that would be easier than using
isspacecheck for each character.– John Elaine
Jun 28 '17 at 23:53
@JohnElaine What's your source encoding, and can you convert to UTF-32? Checking for whitespace is easiest in UTF-32. Basically, I would get line-by-line, convert to UTF-32, iterate code point by code point and check if each is whitespace and process token-by-token. It's not pretty, but it can be pretty easy to do. If you do not want to convert to UTF-32, you could look character by character in UTF-8: if it's an ASCII character (< 128), check against known ASCII space characters, otherwise, fill to a uint32_t.
– Alexander Huszagh
Jun 29 '17 at 0:03