I am new to Arduino and am a beginner in programming. How do I convert a single char to a string (for example, 'c' to "c") and then append the string "c" to string called data?
Consider the following and see if that helps. I think the Arduino String class is overloaded to do this directly.
char c = 'c';
String data = "something" ;
data = data + c;
Related
So if I have a String
char string[4];
string = "A10";
How Can I get 10 as an Integer.
I tried getting 10 by itself using this but it didn't work.
char string[4];
char string2[2];
string = "A10";
string2[0] = string[1];
string2[1] = string[2];
I don't need to worry about the A, I know how to get that, I need to be able to get the 10 as an integer.
In java you can use the following code to convert string to integer,
int i=Integer.parseInt(s2);
for more information view this website,
https://www.javatpoint.com/java-string-to-int
I have a string coming from PC through serial to a microcontroller (Arduino), e.g.:
"HDD: 55 - CPU: 12.6 - Weather: Cloudy [...] $";
by this function I found:
String inputStringPC = "";
boolean stringCompletePC = false;
void serialEvent() {
while (Serial.available()) {
char inChar = (char)Serial.read();
inputStringPC += inChar;
if (inChar == '$') // end marker of the string
{
stringCompletePC = true;
}
}
}
I would like to extract the first number of it after the word HDD, CPU and also get the string after Weather (ie "cloudy"); my thinking is something like that:
int HDD = <function that does that>(Keyword HDD);
double CPU = <function that does that>(Keyword CPU);
char Weather[] = <function that does that>(Keyword Weather);
What is the right function to do that?
I looked into inputStringSerial.indexOf("HDD") but I am still a learner to properly understand what it does and don't know if theres a better function.
My approach yielded some syntax errors and confused me with the difference in usage between "String inputStringSerial" (class?) and "char inputStringSerial[]" (variable?). When I do 'string inputStringSerial = "";' PlatformIO complains that "string" is undefined. Any help to understand its usage here is greatly appreciated.
Thanks a bunch.
The String class provides member functions to search and copy the contents of the String. That class and all its member functions are documented in the Arduino Reference:
https://www.arduino.cc/reference/tr/language/variables/data-types/stringobject/
The other way a list of characters can be represented is a char array, confusingly also called a string or cstring. The functions to search and copy the contents of a char array are documented at
http://www.cplusplus.com/reference/cstring/
Here is a simple Sketch that copies and prints the value of the Weather field using a String object. Use this same pattern - with different head and terminator values - to copy the string values of the other fields.
Once you have the string values of HDD and CPU, you'll need to call functions to convert those string values into int and float values. See the String member functions toInt() and toFloat() at
https://www.arduino.cc/reference/en/language/variables/data-types/string/functions/toint/
or the char array functions atoi() and atof() at
http://www.cplusplus.com/reference/cstdlib/atoi/?kw=atoi
String inputStringPC = "HDD: 55 - CPU: 12.6 - Weather: Cloudy [...] $";
const char headWeather[] = "Weather: "; // the prefix of the weather value
const char dashTerminator[] = " -"; // one possible suffix of a value
const char dollarTerminator[] = " $"; // the other possible suffix of a value
void setup() {
int firstIndex; // index into inputStringPC of the first char of the value
int lastIndex; // index just past the last character of the value
Serial.begin(9600);
// find the Weather field and copy its string value.
// Use similar code to copy the values of the other fields.
// NOTE: This code contains no error checking for unexpected input values.
firstIndex = inputStringPC.indexOf(headWeather);
firstIndex += strlen(headWeather); // firstIndex is now the index of the char just past the head.
lastIndex = inputStringPC.indexOf(dollarTerminator, firstIndex);
String value = inputStringPC.substring(firstIndex, lastIndex);
Serial.print("Weather value = '");
Serial.print(value);
Serial.println("'");
}
void loop() {
// put your main code here, to run repeatedly:
}
When run on an Arduio Uno, this Sketch produces:
Weather value = 'Cloudy [...]'
I have some code that I have no clue why it isn't working.
The code takes a serial input in the form of "xxx,yyy,zzz", where digits can range from 1 to 3 in each number. Because of an odd quirk in an app, it needs to be read as a char, then converted to a string to be handled. The intention is to split into 3 ints, red green and blue, from "RRR,GGG,BBB".
Now this works fine when I manually define String str (see commented code), but when I go and enter it from the serial console, it doesn't want to work. It seems to be coming from the indexOf(',') part, as while using Serial.print(c1);, I found that when I manually entered a string, it returned an index of the comma, but when I used the serial console, it returned -1 (not found).
And yes, the entered string into the console is in the correct format of "RRR,GGG,BBB", I've confirmed that by printing both phone and str independently.
while (Serial.available() > 0) {
char phone = Serial.read();
String str = String(phone);
//String str = "87,189,183";
int ln = str.length()-1;
int c1 = str.indexOf(','); //first place to cut string
int c2 = str.indexOf(',',c1+1); //second place
red = str.substring(0,c1).toInt();
green = str.substring(c1,c2).toInt();
blue = str.substring(c2,ln).toInt();
Serial.print(red);
Edit: With the Arduino String class, creating a string from a char is returning more than just one character, eleven in fact.
This:
char phone = Serial.read();
String str = String(phone);
will never create a string in str that has more than 1 character, since that's what you say you want.
This is the code for the Arduino's String(char) constructor:
String::String(char c)
{
init();
char buf[2];
buf[0] = c;
buf[1] = 0;
*this = buf;
}
So clearly your code will create a 1-character long string.
Also, beware of using indexes computed on the full string, on substrings later.
I'm try to guess that you are using these serial API http://playground.arduino.cc/Interfacing/CPPWindows.
while (Serial.available() > 0) {
char buf[12];
int len = Serial.ReadData(buf,11);
String str = String(buf);
//String str = "87,189,183";
int ln = str.length()-1;
int c1 = str.indexOf(','); //first place to cut string
int c2 = str.indexOf(',',c1+1); //second place
red = str.substring(0,c1).toInt();
green = str.substring(c1,c2).toInt();
blue = str.substring(c2,ln).toInt();
Serial.print(red);
If you are using other API like http://arduino.cc/en/Serial/Read you should follow these API where Serial is a Stream and read() return just the first available char.
Code was fixed by using a different function.
while (Serial.available() > 0) {
char phone = Serial.read();
str += phone;
//String str = "87,189,183";
int ln = str.length()-1;
int c1 = str.indexOf(','); //first place to cut string
int c2 = str.indexOf(',',c1+1); //second place
red = str.substring(0,c1).toInt();
green = str.substring(c1,c2).toInt();
blue = str.substring(c2,ln).toInt();
Serial.print(red);
I'm not sure why this works, and why before I was getting a string with more than one character. But it works!
I'm trying to figure the best way of encoding text (either 8-bit ubyte[] or string) to its HTML counterpart.
My proposal so far is to use a lookup-table to map the 8-bit characters
string[256] lutLatin1ToHTML;
lutLatin1ToXML[0x22] = """;
lutLatin1ToXML[0x26] = "&";
...
in HTML that have special meaning using the function
pure string toHTML(in string src,
ref in string[256] lut) {
return src.map!(a => (lut[a] ? lut[a] : new string(a))).reduce!((a, b) => a ~ b) ;
}
I almost work except for the fact that I don't know how to create a string from a `ubyte? (the no-translation case).
I tried
writeln(new string('a'));
but it prints garbage and I don't know why.
For more details on HTML encoding see https://en.wikipedia.org/wiki/Character_entity_reference
You can make a string from a ubyte most easily by doing "" ~ b, for example:
ubyte b = 65;
string a = "" ~ b;
writeln(a); // prints A
BTW, if you want to do a lot of html stuff, my dom.d and characterencodings.d might be useful:
https://github.com/adamdruppe/misc-stuff-including-D-programming-language-web-stuff
It has a html parser, dom manipulation functions similar to javascript (e.g. ele.querySelector(), getElementById, ele.innerHTML, ele.innerText, etc.), conversion from a few different character encodings, including latin1, and outputs ascii safe html with all special and unicode characters properly encoded.
assert(htmlEntitiesEncode("foo < bar") == "foo < bar";
stuff like that.
In this case Adam's solution works just fine, of course. (It takes advantage of the fact that ubyte is implicitly convertible to char, which is then appended to the immutable(char)[] array for which string is an alias.)
In general the safe way of converting types is to use std.conv.
import std.stdio, std.conv;
void main() {
// utf-8
char cc = 'a';
string s1 = text(cc);
string s2 = to!string(cc);
writefln("%c %s %s", cc, s1, s2);
// utf-16
wchar wc = 'a';
wstring s3 = wtext(wc);
wstring s4 = to!wstring(wc);
writefln("%c %s %s", wc, s3, s4);
// utf-32
dchar dc = 'a';
dstring s5 = dtext(dc);
dstring s6 = to!dstring(dc);
writefln("%c %s %s", dc, s5, s6);
ubyte b = 65;
string a = to!string(b);
}
NB. text() is actually intended for processing multiple arguments, but is conveniently short.
I´m trying to set a random number in a string, but idk how i can let the program know that i want the random number and not the letter n.
Im using visual studio 2008 , Windows Forms C++
System::Drawing::Font ^Fuente = gcnew System::Drawing::Font("Arial Black",50);
System::Random ^r = gcnew System::Random(System::DateTime::Now.Ticks);
char n=r->Next(1,100);
buffer->Graphics->DrawString("n",Fuente,System::Drawing::Brushes::WhiteSmoke,50,50);,50);
System::Drawing::Font ^Fuente = gcnew System::Drawing::Font("Arial Black",50);
System::Random ^r = gcnew System::Random(System::DateTime::Now.Ticks);
int n=r->Next(1,100);
buffer->Graphics->DrawString(n.ToString(), Fuente, System::Drawing::Brushes::WhiteSmoke,50,50);,50);
Might be what you are after
You're using quotes when drawing string - that's a string literal.
You should convert your number to a string using stdlib.h itoa function.
char number[3];
int n = r->Next(1,100);
itoa(n, number, 10); //number to convert, string to save value in, base
buffer->Graphics->DrawString(number,Fuente,System::Drawing::Brushes::WhiteSmoke,50,50);,50);