I want to get first word of a Qstring.
For example String1 = "Read from file1". I want to extract string2 = "Read".
I want to extract substring based on whitespace.
If I encounter a first whitespace in my string1, I need that part of string1 to string2.
Use the split function of QString in this way:
QString firstWord = string1.split(" ").at(0);
If there is no whitespace in the string, the whole string will be returned.
Use QString::split if you want to use all the parts, or QString::section if you just want to grab the first word.
For example, the most basic syntax is:
QString str = "Do re mi";
QString firstWord = str.section(" ", 0, 0);
// firstWord = "Do"
If you need to handle all kinds of weird whitespace, you can use the regex version of the functions:
QString str = "\tDo re\nmi"; // tabs and newlines and spaces, oh my!
QString firstWord = str.section(QRegExp("\\s+"), 0, 0,
QString::SectionSkipEmpty);
// firstWord = "Do"
I would do:
QString s("Read from file1");
QString subStr = s.section(" ", 0, 0, QString::SectionSkipEmpty);
This will work correctly in case of such strings too:
" Read from file1 "
Related
How do you store a certain part of a string into a variable?
For example:
x = myString // - But store the 9th character into a variable
Try this,
x = string_char_at(myString , 9);
This gets a single character from a string:
var x = string_char_at("This is my string", 4); //X == "s"
And you can use the string_copy function to copy parts of a string;
var x = string_copy("This is my string", 8, 2); //X == "my"
My program reads a line from a file. This line contains comma-separated text like:
123,test,444,"don't split, this",more test,1
I would like the result of a split to be this:
123
test
444
"don't split, this"
more test
1
If I use the String.split(","), I would get this:
123
test
444
"don't split
this"
more test
1
In other words: The comma in the substring "don't split, this" is not a separator. How to deal with this?
You can try out this regex:
str.split(",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)");
This splits the string on , that is followed by an even number of double quotes. In other words, it splits on comma outside the double quotes. This will work provided you have balanced quotes in your string.
Explanation:
, // Split on comma
(?= // Followed by
(?: // Start a non-capture group
[^"]* // 0 or more non-quote characters
" // 1 quote
[^"]* // 0 or more non-quote characters
" // 1 quote
)* // 0 or more repetition of non-capture group (multiple of 2 quotes will be even)
[^"]* // Finally 0 or more non-quotes
$ // Till the end (This is necessary, else every comma will satisfy the condition)
)
You can even type like this in your code, using (?x) modifier with your regex. The modifier ignores any whitespaces in your regex, so it's becomes more easy to read a regex broken into multiple lines like so:
String[] arr = str.split("(?x) " +
", " + // Split on comma
"(?= " + // Followed by
" (?: " + // Start a non-capture group
" [^\"]* " + // 0 or more non-quote characters
" \" " + // 1 quote
" [^\"]* " + // 0 or more non-quote characters
" \" " + // 1 quote
" )* " + // 0 or more repetition of non-capture group (multiple of 2 quotes will be even)
" [^\"]* " + // Finally 0 or more non-quotes
" $ " + // Till the end (This is necessary, else every comma will satisfy the condition)
") " // End look-ahead
);
Why Split when you can Match?
Resurrecting this question because for some reason, the easy solution wasn't mentioned. Here is our beautifully compact regex:
"[^"]*"|[^,]+
This will match all the desired fragments (see demo).
Explanation
With "[^"]*", we match complete "double-quoted strings"
or |
we match [^,]+ any characters that are not a comma.
A possible refinement is to improve the string side of the alternation to allow the quoted strings to include escaped quotes.
Building upon #zx81's answer, cause matching idea is really nice, I've added Java 9 results call, which returns a Stream. Since OP wanted to use split, I've collected to String[], as split does.
Caution if you have spaces after your comma-separators (a, b, "c,d"). Then you need to change the pattern.
Jshell demo
$ jshell
-> String so = "123,test,444,\"don't split, this\",more test,1";
| Added variable so of type String with initial value "123,test,444,"don't split, this",more test,1"
-> Pattern.compile("\"[^\"]*\"|[^,]+").matcher(so).results();
| Expression value is: java.util.stream.ReferencePipeline$Head#2038ae61
| assigned to temporary variable $68 of type java.util.stream.Stream<MatchResult>
-> $68.map(MatchResult::group).toArray(String[]::new);
| Expression value is: [Ljava.lang.String;#6b09bb57
| assigned to temporary variable $69 of type String[]
-> Arrays.stream($69).forEach(System.out::println);
123
test
444
"don't split, this"
more test
1
Code
String so = "123,test,444,\"don't split, this\",more test,1";
Pattern.compile("\"[^\"]*\"|[^,]+")
.matcher(so)
.results()
.map(MatchResult::group)
.toArray(String[]::new);
Explanation
Regex [^"] matches: a quote, anything but a quote, a quote.
Regex [^"]* matches: a quote, anything but a quote 0 (or more) times , a quote.
That regex needs to go first to "win", otherwise matching anything but a comma 1 or more times - that is: [^,]+ - would "win".
results() requires Java 9 or higher.
It returns Stream<MatchResult>, which I map using group() call and collect to array of Strings. Parameterless toArray() call would return Object[].
You can do this very easily without complex regular expression:
Split on the character ". You get a list of Strings
Process each string in the list: Split every string that is on an even position in the List (starting indexing with zero) on "," (you get a list inside a list), leave every odd positioned string alone (directly putting it in a list inside the list).
Join the list of lists, so you get only a list.
If you want to handle quoting of '"', you have to adapt the algorithm a little bit (joining some parts, you have incorrectly split of, or changing splitting to simple regexp), but the basic structure stays.
So basically it is something like this:
public class SplitTest {
public static void main(String[] args) {
final String splitMe="123,test,444,\"don't split, this\",more test,1";
final String[] splitByQuote=splitMe.split("\"");
final String[][] splitByComma=new String[splitByQuote.length][];
for(int i=0;i<splitByQuote.length;i++) {
String part=splitByQuote[i];
if (i % 2 == 0){
splitByComma[i]=part.split(",");
}else{
splitByComma[i]=new String[1];
splitByComma[i][0]=part;
}
}
for (String parts[] : splitByComma) {
for (String part : parts) {
System.out.println(part);
}
}
}
}
This will be much cleaner with lambdas, promised!
Please see the below code snippet. This code only considers happy flow. Change the according to your requirement
public static String[] splitWithEscape(final String str, char split,
char escapeCharacter) {
final List<String> list = new LinkedList<String>();
char[] cArr = str.toCharArray();
boolean isEscape = false;
StringBuilder sb = new StringBuilder();
for (char c : cArr) {
if (isEscape && c != escapeCharacter) {
sb.append(c);
} else if (c != split && c != escapeCharacter) {
sb.append(c);
} else if (c == escapeCharacter) {
if (!isEscape) {
isEscape = true;
if (sb.length() > 0) {
list.add(sb.toString());
sb = new StringBuilder();
}
} else {
isEscape = false;
}
} else if (c == split) {
list.add(sb.toString());
sb = new StringBuilder();
}
}
if (sb.length() > 0) {
list.add(sb.toString());
}
String[] strArr = new String[list.size()];
return list.toArray(strArr);
}
Hey im looking for a way to do the following to populate a text file
if I need to fill a alphanumeric column with Field size 20 and I only have 18 characters to append two blank values.
then same for numeric values if field size is 10 for example and i have a value of 5 characters to fill in remaining spaces with 5 0's
i.e instead of 10000 i would have 0000010000
string s = "10000";
string t = s.PadLeft(20, '0');
The PadLeft method should do the trick. Something like this:
var output = myTextString.PadLeft(20);
or
var output = myNumericString.PadLeft(10, '0');
Here's some pseudocode that should do it:
int size = mystring.length();
int padding = 20 - size;
string pad = "";
for(padding){
pad += "0";
}
string newstring = pad + mystring;
http://jsfiddle.net/qtzTu/
How to Pad a Number with Leading Zeroes:
http://msdn.microsoft.com/en-us/library/dd260048.aspx
The OP implied the string lengths would vary, so here is a Func where you won't have to hard code values like "10" or "20"
Func<string, int, string> PadStringToSize = (x,y)
=> (x.Length < y ? x.PadLeft(y, '0') : x);
You can then do things like:
Console.WriteLine(PadStringToSize("10000", 10)); // Pads to 10
Console.WriteLine(PadStringToSize("10000", 30)); // Pads to 30
Then you can just wrap the call to a method that takes the size as a parameter instead hard coding the desired length.
I am trying to read a text file using Dynamics AX. However, the following code replaces any spaces in the lines with commas:
// Open file for read access
myFile = new TextIo(fileName , 'R');
myFile.inFieldDelimiter('\n');
fileRecord = myFile.read();
while (fileRecord)
{
line = con2str(fileRecord);
info(line);
…
I have tried various combinations of the above code, including specifying a blank '' field delimiter, but with the same behaviour.
The following code works, but seems like there should be a better way to do this:
// Open file for read access
myFile = new TextIo(fileName , 'R');
myFile.inRecordDelimiter('\n');
myFile.inFieldDelimiter('_stringnotinfile_');
fileRecord = myFile.read();
while (fileRecord)
{
line = con2str(fileRecord);
info(line);
The format of the file is field format. For example:
DATAFIELD1 DATAFIELD2 DATAFIELD3
DATAFIELD1 DATAFIELD3
DATAFIELD1 DATAFIELD2 DATAFIELD3
So what I end up with unless I use the workaround above is something like:
line=DATAFIELD1,DATAFIELD2,DATAFIELD3
The underlying problem here is that I have mixed input formats. Some of the files just have line feeds {LF} and others have {CR}{LF}. Using my workaround above seems to work for both. Is there a way to deal with both, or to strip \r from the file?
Con2Str:
Con2Str will retrieve a list of values from a container and by default uses comma (,) to separate the values.
client server public static str Con2Str(container c, [str sep])
If no value for the sep parameter is specified, the comma character will be inserted between elements in the returned string.
Possible options:
If you would like the space to be the default separator, you can pass space as the second parameter to the method Con2Str.
One other option is that you can also loop through the container fileRecord to fetch the individual elements.
Code snippet 1:
Below code snippet loads the file contents into textbuffer and replace the carriage returns (\r) with new line (\n) character. The condition if (strlen(line) > 1) will help to skip empty strings due to the possible occurrence of consecutive newline characters.
TextBuffer textBuffer;
str textString;
str clearText;
int newLinePos;
str line;
str field1;
str field2;
str field3;
counter row;
;
textBuffer = new TextBuffer();
textBuffer.fromFile(#"C:\temp\Input.txt");
textString = textBuffer.getText();
clearText = strreplace(textString, '\r', '\n');
row = 0;
while (strlen(clearText) > 0 )
{
row++;
newLinePos = strfind(clearText, '\n', 1, strlen(clearText));
line = (newLinePos == 0 ? clearText : substr(clearText, 1, newLinePos));
if (strlen(line) > 1)
{
field1 = substr(line, 1, 14);
field2 = substr(line, 15, 12);
field3 = substr(line, 27, 10);
info('Row ' + int2str(row) + ', Column 1: ' + field1);
info('Row ' + int2str(row) + ', Column 2: ' + field2);
info('Row ' + int2str(row) + ', Column 3: ' + field3);
}
clearText = (newLinePos == 0 ? '' : substr(clearText, newLinePos + 1, strlen(clearText) - newLinePos));
}
Code snippet 2:
You could use File macro instead of hard coding the values \r\n and R that denotes the read mode.
TextIo inputFile;
container fileRecord;
str line;
str field1;
str field2;
str field3;
counter row;
;
inputFile = new TextIo(#"c:\temp\Input.txt", 'R');
inputFile.inFieldDelimiter("\r\n");
row = 0;
while (inputFile.status() == IO_Status::Ok)
{
row++;
fileRecord = inputFile.read();
line = con2str(fileRecord);
if (line != '')
{
field1 = substr(line, 1, 14);
field2 = substr(line, 15, 12);
field3 = substr(line, 27, 10);
info('Row ' + int2str(row) + ', Column 1: ' + field1);
info('Row ' + int2str(row) + ', Column 2: ' + field2);
info('Row ' + int2str(row) + ', Column 3: ' + field3);
}
}
Never tried to use the default RecordDelimiter as FieldDelimiter and not setting another RecordDelimiter explicitly. Normally rows (Records) are delimited by \n and fields are delimited by comma, tab, semicolon or some other symbol. You might also be hitting some weird behaviour when TextIO is assuming correct UTF-format. You didn't supply an example of some rows from you datafile, so guessing is hard.
Read more about TextIO here: http://msdn.microsoft.com/en-us/library/aa603840.aspx
EDIT:
With the additional example of file content, it seems to me the file is a fixed width file, where each column has its own fixed width. I would rather recommend using subStr if that is the case. Read about substr here: http://msdn.microsoft.com/en-us/library/aa677836.aspx
use StrAlpha to restrict blank values after you convert Con2Str
can you please help me with this issue the String class does not have insert method it has only replace :( .
what I need is:
- if I have string "I stackoverflow"
- I need to insert "love " at index 2 to have "I love stackoverflow"
so what I need is insertAt(index, String)
thanks
You can build one of your own. Split the string and concatenate all characters before the index position with the characters of the string you want to insert and with the characters after the index.
eg:
String s = "I stackoverflow";
int index = s.indexOf(" ");
String toInsert = "love ";
String mys = s.substring(0, index) + toInsert + s.substring(index, s.length);
var s:String = "I StackOverflow";
var t:String = s.split(" ").join(" love ");