I am trying to get a special character (ASCII >127) from a string after I set it there, but the output is changing because CharToStr accepts uchar, and StringGetChar returns ushort.
This is what I've tried:
uchar uch = 234;
Print(uch); //Output: 234
string a = CharToStr(uch);
uch = (uchar)StringGetChar(a,0);
Print(uch); //Output: 218
How can I overcome this issue?
I want to suggest my own answer.
Instead of dealing with uchar <==> ushort, which is problematic due to the continous bug in MQL4, you may recode it this way:
//let's say it can be any number, unknown in compilation time
string msg = "234My message";
//then somewhere in the code when you want to display the message:
uchar arrow = (uchar)StringToInteger(StringSubstr(msg,0,3));
//and act upon this arrow, now that you have the correct code:
if(arrow==234) { ... }
else if (arrow==233) { ... }
Related
I have a String with different value every time:
String words = "My name is Rob Joe";
I want to get only last word
Joe
but every time I don't know how many words the string consists of
String words = "My name is Rob Joe";
var array = words.split(" "); // <-- [My, name, is, Rob, Joe]
print(array.last); // output 'Joe'
In Flutter(Dart), you can get the last word of a string by splitting the string into an array of substrings using the split method and then accessing the last element of the resulting array. Here's an example:
String words = "My name is Rob Joe";
List<String> wordsArray = myString.split(" ");
String lastWord = wordsArray[wordsArray.length - 1];
print(lastWord); // "Joe"
Instead of splitting, you can also use substring and lastIndexOf:
final words = "My name is Rob Joe";
final lastWord = words.substring(words.lastIndexOf(" ") + 1);
print(lastWord);
If you want to find the last word, you should first properly define what a "word" is.
It's clearly obvious here, which is why it's doubly important to write it down, because something else may be just as obvious to someone else.
(Read: Nothing is obvious. Document it all!)
But let's say that a word is a maximal contiguous sequence of ASCII letters.
Then that's what you should look for.
Splitting on space characters works for this string, but won't if you have punctuation, or trailing whitespace, or any number of other complications.
I'd probably use a RegExp:
// Matches a word. If used properly, only matches entire words.
var wordRE = RegExp(r"[a-zA-Z]+");
// Assume at least one word in `words`. Otherwise need more error handling.
var lastWord = wordRe.allMatches(words).last[0]!;
This can be a little inefficient, if the string is long.
Another approach that might be more efficient, depending on the RegExp implementation, is to search backwards:
/// Captures first sequence of [a-zA-Z]+ looking backwards from end.
var lastWordRE = RegExp(r"$(?<=([a-zA-Z]+)[^a-zA-Z]*)");
var lastWord = lastWordRE.firstMatch(words)?[1]!;
If you don't want to rely on RegExps (which are admittedly not that readable, and their performance is not always predictable), you can search for letters manually:
String? lastWord(String words) {
var cursor = words.length;
while (--cursor >= 0) {
if (_isLetter(words, cursor)) {
var start = 0;
var end = cursor + 1;
while (--cursor >= 0) {
if (!_isLetter(words, prev)) {
start = cursor + 1;
break;
}
}
return words.substring(start, end);
}
}
return null;
}
bool _isLetter(String string, int index) {
var char = string.codeUnitAt(index) | 0x20; // lower-case if letter.
return char >= 0x61 /*a*/ && char <= 0x7a /*z*/;
}
But first of all, decide what a word is.
Some very real words in common sentences might contain, e.g., ' or -, but whether they matter to you or not depends on your use-case.
More exotic cases may need you to decide whether"e.g." is one word or two? Is and/or? Is i18n?
Depends on what it'll be used for.
I'm trying to create a variable format specifier for use in $display/$write. I've tried a large number of things, but here is what I have at the moment.
What I want to end up with is: $display(format_var,data_1,data_2), where the format string is pre-calculated using $sformatf or other.
Code:
module test;
function void pprint(input int data_1,input int field_1,input int data_2,input int field_2);
string format;
begin
format = $sformatf("%0d'h%%%0dx,%0d'h%%%0dx",field_1,field_1/4,field_2,field_2/4);
$display("format = %s",format);
$display(format,data_1,data_2);
end
endfunction
initial
begin
pprint(5,8,73737229,128);
$stop;
end
endmodule
The output I expect is:
format = 8'h%2x,128'h%32x
8'h05,128'h000000000000000000000000465240D
The output I get is:
format = 8'h%2x,128'h%32x
8'h%2x,128'h%32x 5 73737229
What do I need to do? The simulator is Vivado 2020.3
Later:
Trying more things, the following function does do what I want. My conclusion is that $display/$write can't take a variable as the format string, but $sformatf can.
function void pprint(input int data_1,input int field_1,input int data_2,input int field_2);
string format;
string outstr;
begin
format = $sformatf("%0d'h%%%0dx,%0d'h%%%0dx",field_1,field_1/4,field_2,field_2/4);
$display("format = %s",format);
$display("%s",$sformatf(format,data_1,data_2));
end
endfunction
Try:
function void pprint(
input logic [4095:0] data_1,
input int field_1,
input logic [4095:0] data_2,
input int field_2 );
string format;
format = $sformatf("%0d'h%%%0dh,%0d'h%%%0dh",
field_1, (field_1+3)/4,
field_2, (field_2+3)/4 );
$display("format = %s",format);
$display($sformatf(format,data_1,data_2));
endfunction
This should give you the output:
format = 8'h%02h,128'h%032h
8'h05,128'h000000000000000000000000465240D
Adding a zero between the % and digit could tells the simulator to pad the upper bits with zeros.
For some reason $display(format,data_1,data_2) did not use the format on simulators on edaplayground, but it did work with $sformatf so I simply nested it.
I needed to increase the bit width of the input data otherwise it would show leading zeros over 8 digits. Adjust if necessary.
Adding 3 to the field is for handling non multiples of 4. It will always round down after division.
According to section 21.3.3 Formatting data to a string of the SystemVerilog LRM, only $sformat and $sformatf have a specific formatting argument that can be a string literal or string variable. All other output tasks like $display treat any string literal argument as format specifiers and do not interpret the strings inside string variables for formatting.
How do you write a Binary Literal in Dart?
I can write a Hex Literal like so:
Int Number = 0xc
If I try the conventional way to write a Binary Literal:
Int Number = 0b1100
I get an error. I've tried to look it up, but I've not been able to find any information other than for hex.
There are currently no built-in binary number literals in Dart (or any base other than 10 and 16).
The closest you can get is: var number = int.parse("1100", radix: 2);.
Maybe you can use this:
// 0b1100 -> 1 at 3th bit and 1 at 2nd bit
final number = 1 << 3 | 1 << 2;
// Print binary string
print(number.toRadixString(2)) // 1100
Try binary package:
import 'package:binary/binary.dart';
void main() {
// New API.S
print(0x0C.toBinaryPadded(8)); // 00001100
}
see: https://pub.dev/documentation/binary/latest/
I'm writing a function to replace substrings (what laguange doesn't have this, grr), and I am getting some strange characters in my ouput. I cannot figure out why.
string replaceSubstring(string input, string targetSubstring, string substitute, bool matchCase)
{
string result = input
Buffer b = create
b = input
int targetStartPos
int targetLength
while (findPlainText(result, targetSubstring, targetStartPos, targetLength, matchCase))
{
string prefixStr = b[0:targetStartPos - 1]
string suffixStr = b[targetStartPos + targetLength:]
b = prefixStr substitute suffixStr
result = tempStringOf(b)
}
delete b
return result
}
When running print replaceSubstring("Jake Lewis", "ake", "ack", false), I get an output of �*��*�is. This would appear to be some sort of encoding issue, but I am unclear on how this is happening, or how to fix it.
Try using stringOf() instead of tempStringOf(). Your processing is fine, but the result becomes invalid after deleting b.
I wanted to know how does writeInt treat a 32 bit unsigned or a signed integer passed to it?
It is easy to understand that how it works with a hexadecimal number. Util.Print will print the corresponding ASCII Characters.
0x41424344 will be broken down into 4 1 byte characters, A, B, C and D.
It seems like its different when an integer is passed to writeInt.
for instance,
var test: ByteArray = new ByteArray();
test.writeInt(0x41424344); // prints ABCD
test.writeInt(2590463591); // prints gVg
test.writeInt(1119885898); // prints BÀJ
I am unclear how the Util.Print function treats the integers written into the ByteArray by writeInt.
The characters, gVg do not correspond to the integer number, 2590463591
According to the definition of writeInt here:
http://livedocs.adobe.com/livecycle/es/sdkHelp/common/langref/flash/utils/ByteArray.html#writeInt%28%29
It states that it works with a 32 Bit Signed Integer.
If someone can elaborate over how it translates the integers to characters, it would be helpful.
EDIT: And how does it handle negative integers?
For instance,
test.writeInt(-11338743); // prints ÿRü
So,
-11338743 = 0xFF52FC09
is that correct?
Thanks.
If you interpret encoded bytes as ASCII
dec hex ascii
1094861636 = 0x41424344 = ABCD
2590463591 = 0x9A675667 = gVg
1119885898 = 0x42C01A4A = BÀJ
Also, note that int vs unsigned int would implement different functions:
var test:ByteArray = new ByteArray();
test.writeInt(0x41424344);
test.writeUnsignedInt(0x41424344);