I would like to access an index of a string (e.g. 'Hello') and print it to the app (e.g. letter 'o'). This string has to be the input of the user.
This can be easily done using Python but I have to use Flutter/Dart in order to do it (mobile development).
Here is just an example of how this would be solve using Python:
my_word = input("Insert your word here: ")
print(my_word[4])
Use TextField to retrieve user's input:
A text field lets the user enter text, either with hardware keyboard
or with an onscreen keyboard.
Use Text to display the string that you retrieve:
The Text widget displays a string of text with single style.
Use the [] (index) operator to get the character at the index you specify:
final str = "Hello World";
print(str[4]); // Prints o
You can try split the string's letters in an array first.
my_word.split('')[4]
main() {
String val = "hello";
print(val[4]);
}
Related
I want to pass a text value from my NFC tag to a variable, but want to remove the locale from the text passed to the variable (note, not remove it from the tag).
I am using the nfc_manager package.
Here is the code portion I am using that relates to scanning the tag:
NfcManager.instance.startSession(
onDiscovered: (NfcTag tag) async {
final ndef = Ndef.from(tag);
String tagRecordText = String.fromCharCodes(ndef!.cachedMessage!.records[0].payload);
NfcManager.instance.stopSession();
}
)
The first byte is the length of the characters of the language string
So this should work (my dart is not that good)
var payload = ndef!.cachedMessage!.records[0].payload;
var sub = payload.sublist(payload[0]+ 1);
String tagRecordText = String.fromCharCodes(sub);
The detail specs of a Text Record
For interaction with an API, I need to pass the course code in <string><space><number> format. For example, MCTE 2333, CCUB 3621, BTE 1021.
Yes, the text part can be 3 or 4 letters.
Most users enter the code without the space, eg: MCTE2333. But that causes error to the API. So how can I add a space between string and numbers so that it follows the correct format.
You can achieve the desired behaviour by using regular expressions:
void main() {
String a = "MCTE2333";
String aStr = a.replaceAll(RegExp(r'[^0-9]'), ''); //extract the number
String bStr = a.replaceAll(RegExp(r'[^A-Za-z]'), ''); //extract the character
print("$bStr $aStr"); //MCTE 2333
}
Note: This will produce the same result, regardless of how many whitespaces your user enters between the characters and numbers.
Try this.You have to give two texfields. One is for name i.e; MCTE and one is for numbers i.e; 1021. (for this textfield you have to change keyboard type only number).
After that you can join those string with space between them and send to your DB.
It's just like hack but it will work.
Scrolling down the course codes list, I noticed some unusual formatting.
Example: TQB 1001E, TQB 1001E etc. (With extra letter at the end)
So, this special format doesn't work with #Jahidul Islam's answer. However, inspired by his answer, I manage to come up with this logic:
var code = "TQB2001M";
var i = course.indexOf(RegExp(r'[^A-Za-z]')); // get the index
var j = course.substring(0, i); // extract the first half
var k = course.substring(i).trim(); // extract the others
var formatted = '$j $k'.toUpperCase(); // combine & capitalize
print(formatted); // TQB 1011M
Works with other formats too. Check out the DartPad here.
Here is the entire logic you need (also works for multiple whitespaces!):
void main() {
String courseCode= "MMM 111";
String parsedCourseCode = "";
if (courseCode.contains(" ")) {
final ensureSingleWhitespace = RegExp(r"(?! )\s+| \s+");
parsedCourseCode = courseCode.split(ensureSingleWhitespace).join(" ");
} else {
final r1 = RegExp(r'[0-9]', caseSensitive: false);
final r2 = RegExp(r'[a-z]', caseSensitive: false);
final letters = courseCode.split(r1);
final numbers = courseCode.split(r2);
parsedCourseCode = "${letters[0].trim()} ${numbers.last}";
}
print(parsedCourseCode);
}
Play around with the input value (courseCode) to test it - also use dart pad if you want. You just have to add this logic to your input value, before submitting / handling the input form of your user :)
How to display Unicode Smiley from json response dynamically in flutter. It's display properly when i declare string as a static but from dynamic response it's not display smiley properly.
Static Declaration: (Working)
child: Text("\ud83d\ude0e\ud83d\ude0eThis is just test notification..\ud83d\ude0e\ud83d\ude0e\ud83d\udcaf\ud83d\ude4c")
Dynamic Response:
"message":"\\ud83d\\ude4c Be Safe at your home \\ud83c\\udfe0",
When i'm parse and pass this response to Text then it's consider Unicode as a String and display as a string instead of Smiley Code is below to display text with smiley:
child: Text(_listData[index].message.toString().replaceAll("\\\\", "\\"))
Already go through this: Question but it's only working when single unicode not working with multiple unicode.
Anyone worked with text along with unicode caracter display dynamically then please let me know.
Another alternate Good Solution I would give to unescape characters is this:
1st ->
String s = "\\ud83d\\ude0e Be Safe at your home \\ud83c\\ude0e";
String q = s.replaceAll("\\\\", "\\");
This would print and wont be able to escape characters:
\ud83d\ud83d Be Safe at your home \ud83c\ud83d
and above would be the output.
So what one can do is either unescape them while parsing or use:
String convertStringToUnicode(String content) {
String regex = "\\u";
int offset = content.indexOf(regex) + regex.length;
while(offset > 1){
int limit = offset + 4;
String str = content.substring(offset, limit);
// print(str);
if(str!=null && str.isNotEmpty){
String uni = String.fromCharCode(int.parse(str,radix:16));
content = content.replaceFirst(regex+str,uni);
// print(content);
}
offset = content.indexOf(regex) + regex.length;
// print(offset);
}
return content;
}
This will replace and convert all the literals into unicode characters and result and output of emoji:
String k = convertStringToUnicode(q);
print(k);
😎 Be Safe at your home 🈎
That is above would be the output.
Note: above answer given would just work as good but this is just when you want to have an unescape function and don't need to use third-party libraries.
You can extend this using switch cases with multiple unescape solutions.
Issue resolved by using below code snippet.
Client client = Client();
final response = await client.get(Uri.parse('YOUR_API_URL'));
if (response.statusCode == 200) {
// If the server did return a 200 OK response,
// then parse the JSON.
final extractedData = json.decode(response.body.replaceAll("\\\\", "\\"));
}
Here we need to replace double backslash to single backslash and then decode JSON respone before set into Text like this we can display multiple unicode like this:
final extractedData = json.decode(response.body.replaceAll("\\",
"\"));
Hope this answer help to other
I'm porting my Swift app to Flutter and for localising it I'm following this https://github.com/billylev/flutter_localizations but I can't see how to insert placeholder to insert a value in the translated values.
Basically the guide uses
String text(String key) {
return _localisedValues[key] ?? "$key not found";
}
to get the corresponding key:value pair from a .json file as
{
"Shop": "Negozio",
}
I just pass it in the Textwidget as :
Text(AppLocalizations.instance.text('Shop')).
How to modify text to insert one or more placeholders and how would be the .json be constructed?
Say for the value "User": "User" I'd like to insert a value after the transaction I can simply use a string sum and add the value as `Text(
AppLocalizations.instance.text('User') + ' ${widget.user.name}', but if I need to insert a value in the middle of the translated sentence, eg a message, I don't see how to accomplish it.
I need it to make localised versions of incoming push notification, and they have args.
In Swift I have it like this:
"ORDER_RECEIVED_PUSH_TITLE" = "Order number: %#";
"ORDER_RECEIVED_PUSH_SUBTITLE" = "Shop: %#";
"ORDER_RECEIVED_PUSH_BODY" = "Thank you %#! We received your order and we'll let you know when we start preparing it and when it's ready. Bye";
Any suggestions on how to accomplish that in Flutter?
Many thanks
I was suggested this package https://pub.dev/packages/sprintf#-installing-tab- and it works just as I needed. Sprintf just lets you specify one or more placeholders in a String and pass an array of args.
https://developermemos.com/posts/using-sprintf-flutter-dart. for more info, even this is pretty much it. So for example
"ORDER_RECEIVED_PUSH_TITLE" = "Order number: %#";
in the .json file would be :
{
"ORDER_RECEIVED_PUSH_TITLE": "Oder number: %s"
}
and using it would be
String orderNumber = 'some uuid';
Text(Sprintf(AppLocalitazions.instance.text('ORDER_RECEIVED_PUSH_TITLE'),[orderNumber]);
Hope this helps others.
I can see that Flutter allows me to use "\n\n" in a string and it causes a line break to appear in a Text item:
final String answer = "This is my text.\n\n"
"Here is the 2nd line.";
This is my text.
Here is the 2nd line.
However, when I try to use content pulled from firebase, and set in a variable, the line break ("\n") is actually printed:
final String answer = faq['answer'];
Shows:
This is my text.\n\nHere is the 2nd line.
How can I get my "\n\n" to actually show up as line breaks?
Firestore doesn't support any escape sequences within string values. If you write "\n" in a string, you're going to get exactly that back when you read it.
So you can try something like this:
final String answer = (faq['answer'] as String).replaceAll("\\n", "\n");