so i read and read but i don't understand
let me tell
i have a Array with values
i read one value
ex
buffer , this return FF
but now i wanne have the dec value of FF = 255
how can i do that
i tried
long Ro = strtol(buffer*, NULL, 16);*
but get error
can someone bring me on the right direction
We PRINT values in decimal, hex, octal etc but the valuse never change they are values ( numbers) and there not in hex or dec thats just the way we write them
Mark
Is what you receive this:
char buf[] = "FF";
or this:
int number = 0xFF;
Do you want the number to be this:
char buf[] = "255";
or this:
int number = 255;
This seems like a simple question once things are understood. You might also want to ask in the language specific forums below to get help in your native language.
i receive this
char buf[] = "FF";
and wanne need this
int number = 255;.
something like this
int t0 = buf[0] - '0';
if (t0 >= 10) t0 -= 7;
int t1 = buf[1] - '0';
if (t1 >= 10) t1 -= 7;
int number = t1 *16 + t2;
You can also use the strtol() library function.
Indeed. If that's what you have, this should have worked:
long Ro = strtol(buffer, NULL, 16);
What error did you get?
On an Arduino 'strtol' is an incredibly long and inefficient function. You can do this though:
inline byte hexToByte(char* hex){
byte high = hex[0];
byte low = hex[1];
if (high > '9'){
high -= (('A'-'0')-0xA); //even if hex is lower case (e.g. 'a'), the lower nibble will have the correct value as (('a'-'A')&0x0F) = 0.
}
if (low > '9'){
low -= (('A'-'0')-0xA); //even if hex is lower case (e.g. 'a'), the lower nibble will have the correct value as (('a'-'A')&0x0F) = 0.
}
return (((high & 0xF)<<4) | (low & 0xF));
}
inline unsigned int hexToInt(char* hex){
return ((hexToByte(hex) << 8) | hexToByte(hex+2));
}
inline unsigned long hexToLong(char* hex){
return ((((unsigned long)hexToInt(hex)) << 16) | hexToInt(hex+4));
}
Which can be called for example like this;
char buf[] = "FF";
byte number = hexToByte(buf);
//or
char bigbuf[] = "DEAD";
unsigned int largeNumber = hexToInt(bigbuf);
//or
char hugebuf[] = "DEADBEEF";
unsigned long hugeNumber = hexToLong(hugebuf);
thanks , i will try
I've just edited my last post with a better version which won't change the original string.
receive this error
standv31:71: error: invalid conversion from 'char' to 'char*'
standv31:71: error: initializing argument 1 of 'unsigned int hexToInt(char*)'
this is the code where it happens
Serial.print("-");
Serial.print(buffer[i]);
Serial.print("-");
unsigned int largeNumber = hexToInt(buffer[i]);
Serial.print(largeNumber);
Serial.println("-");
Show me how you declare 'buffer'. (and preferably all of your code)
here is the code
it read data from a SD card
#include <SD.h>
#include <elapsedMillis.h>
#include <TimerOne.h>
#include "LPD6803.h"
const int chipSelect = 4;
char buffer[516];
int dataPin = 2; // 'yellow' wire
int clockPin = 3;
LPD6803 strip = LPD6803(20, dataPin, clockPin);
void setup()
{
strip.setCPUmax(100);
strip.begin();
strip.show();
Serial.begin(115200);
pinMode(LED_BUILTIN, OUTPUT);
digitalWrite(LED_BUILTIN, HIGH);
while (!SD.begin(chipSelect)) {
delay(250);
}
digitalWrite(LED_BUILTIN, LOW);
}
void loop()
{
play();
}
void play()
{
File f = SD.open("COREPLAY.TXT");
if (f) {
long period = f.parseInt();
Serial.print("Period is ");
Serial.println(period);
f.readBytesUntil('\n', buffer, sizeof(buffer));
elapsedMillis msec=0;
while (f.available()) {
f.readBytesUntil('\n', buffer, sizeof(buffer));
Serial.print("Data: ");
Serial.print(buffer);
int channels = hex2bin(buffer);
Serial.print(", ");
Serial.print(channels);
Serial.println(" channels");
if (channels > 0) {
for (int i=0; i < channels; i++) {
//byte Ro = hexToByte(buffer[i]);
//byte Gr = hexToByte(buffer[i++]);
//byte Bl = hexToByte(buffer[i++]);
int c = 0;
//c = Color(Ro,Gr,Bl);
//strip.setPixelColor(i, c);
Serial.print("-");
Serial.print(buffer[i]);
Serial.print("-");
unsigned int largeNumber = hexToInt(buffer[i]);
Serial.print(largeNumber);
Serial.println("-");
}
strip.show();
// wait for the required period
while (msec < period) ; // wait
msec = msec - period;
}
}
f.close();
}
}
byte hexdigit(char c)
{
if (c >= '0' && c <= '9') return c - '0';
if (c >= 'A' && c <= 'F') return c - 'A' + 10;
return 255;
}
int hex2bin(char *buf)
{
byte b1, b2;
int i=0, count=0;
while (1) {
b1 = hexdigit(buf[i++]);
if (b1 > 15) break;
b2 = hexdigit(buf[i++]);
if (b2 > 15) break;
buf[count++] = b1 * 16 + b2;
}
return count;
}
unsigned int Color(byte r, byte g, byte b)
{
//Take the lowest 5 bits of each value and append them end to end
return( ((unsigned int)g & 0x1F )<<10 | ((unsigned int)b & 0x1F)<<5 | (unsigned int)r & 0x1F);
}
inline byte hexToByte(char* hex){
byte high = hex[0];
byte low = hex[1];
if (high > '9'){
high -= (('A'-'0')-0xA); //even if hex is lower case (e.g. 'a'), the lower nibble will have the correct value as (('a'-'A')&0x0F) = 0.
}
if (low > '9'){
low -= (('A'-'0')-0xA); //even if hex is lower case (e.g. 'a'), the lower nibble will have the correct value as (('a'-'A')&0x0F) = 0.
}
return (((high & 0xF)<<4) | (low & 0xF));
}
inline unsigned int hexToInt(char* hex){
return ((hexToByte(hex) << 8) | hexToByte(hex+2));
}
inline unsigned long hexToLong(char* hex){
return ((((unsigned long)hexToInt(hex)) << 16) | hexToInt(hex+4));
}
it's a copy paste code
Yeah, that's not how you would use it.
You'd need to do something like this:
unsigned int largeNumber = hexToInt(buffer+i);
i have some values now , but not what i expected
one line of data is like this
00FF0000FF0000FF000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
i need values for
00
FF
00
and so on
So you would need something like this:
for (int i=0; i < channels; i++) {
Serial.print("-");
byte number = hexToByte(buffer[i<<1]);
Serial.print(number);
Serial.println("-");
}
get error in line
byte number = hexToByte(buffer[i<<1]);
standv31.ino: In function 'void play()':
standv31:77: error: invalid conversion from 'char' to 'char*'
standv31:77: error: initializing argument 1 of 'byte hexToByte(char*)'
Yeah, sorry about that, I modified the code you had posted and forgot to change a bit of it. Try this:
for (int i=0; i < channels; i++) {
Serial.print("-");
byte number = hexToByte(&buffer[i<<1]);
Serial.print(number);
Serial.println("-");
}
hmm ,
also strange values and not what it should be . . .
otherwise i can with a python script generate a dec value file with , as delimiter
but then i need to store every value into a array
i mean
data = "255,255,0,128,2,255" and so on
then then array will look like
storeddata[1] = 255
storeddata[2] = 255
storeddata[3] = 0
storeddata[4] = 128
and so on
i already read that i need strok.
if this way wanne be easier it's no problem for me.