Ok I will try. I'm back in a few houres 

Thank you all ! But if my command is a number, how can I convert the string ?

I was just saying that my problem is probably either my table or value chains of nature, or display on the console. Finally it is revealed that Gobetwino, I think.

In this code, what is not good?
http://arduino.cc/forum/index.php/topic,140381.msg1055282.html#msg1055282

Oh god, I didn't see 
That's work but it's not what I wan't...

But I think the last code I have posted is good but I have a just a problem with my array or with string. I was testing it on Gobetwino when I see "is not a well formed command string" for all I wrote on my program... Can you help me ?

I don't understand much... Plus, I have an error :

Code:

// this constant won't change:
const int  buttonPin = 2;    // the pin that the pushbutton is attached to
const int ledPin = 13;       // the pin that the LED is attached to
const int  buttonPin2 = 3;   // second button to know the numbers of everydays
const int ledPin2 = 8;

// Variables will change:
int buttonPushCounter = 0;   // counter for the number of button presses
int buttonState = 0;         // current state of the button
int buttonState2 = 0;
int lastButtonState = 0;     // previous state of the button
int lastButtonState2 = 0;

double time = 0; // will contain the hour

int numberSaving = 0; //permite to know if the number have been already saved

int i; //to explore the array

//Array which will contain de number of the push by day
int day = 0; //not one because the programm will automatically increment
float counterByDay[] = {}; //this array will begin on 1, not on 0

//Prepare control by console
int numberWanted;
char readString;
boolean stringComplete = false;
int charAvailable;


void setup()
{
  // initialize the button pin as a input:
  pinMode(buttonPin, INPUT);
  pinMode(buttonPin2, INPUT);
  // initialize the LED as an output:
  pinMode(ledPin, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  // initialize serial communication:
  Serial.begin(9600);
 
  // little home message
  Serial.println("------COMPTEUR D'IMPULSIONS-------");
  Serial.println("Nb: appuyer sur le bouton pour obternir les resultats des derniers jours.");
  Serial.println("");
}


void loop() {
  // read the pushbutton input pin:
  buttonState = digitalRead(buttonPin);
  // turns on the LED when button pushed
  digitalWrite(ledPin, buttonState);
 
  // compare the buttonState to its previous state
  if ((buttonState != lastButtonState) && (millis() > 3000)) //"millis() > 3000" permite to avoid the inconvenience of starting
  {
    // if the state has changed, increment the counter
    if (buttonState == HIGH)
    {
      // if the current state is HIGH then the button
      // wend from off to on:
      buttonPushCounter++;
      Serial.print("Compteur:  ");
      Serial.println(buttonPushCounter);
      Serial.println("");
    }
    else {
      // if the current state is LOW then the button
      // wend from on to off:
      Serial.println("+1");
    }
  }
  // save the current state as the last state,
  //for next time through the loop
  lastButtonState = buttonState;
 
  //actualise time
  time = millis();
 
  //preparing time to verify that is a multiple of one day
  time = time/(round(time / 15000));
 
  //if time = one day, save the number
  if ((time >= 15000) && (time <= 15100) && (numberSaving == 0) && (millis() > 3000)) //REAL: if(time >= 86400000 && time <= 86402000)
  {
    //operations to save the number with the date in an array:
    day++;
    counterByDay[day] = buttonPushCounter;
   
    //initialise counter
    buttonPushCounter = 0;
   
    //write it on the sreen
    Serial.println("");
    Serial.println("-----");
    Serial.print("Jour ");
    Serial.print(day);
    Serial.print(", nombre de basculement:  ");
    Serial.println(round(counterByDay[day]));
    Serial.println("-----");
    Serial.println("");
   
    numberSaving = 1;
  }
  //If the number have been saved, and if won't be save a second time, we initialise numberSaving
  else if (((time < 15000) || (time > 15100)) && (numberSaving == 1))
  {
    numberSaving = 0;
  }
 
  //This part must show all the array when button 2 is pressed
  // read the pushbutton2 input pin:
  buttonState2 = digitalRead(buttonPin2);
  // turns on the LED 2 when button pushed
  digitalWrite(ledPin2, buttonState2);
 
  // compare the buttonState2 to its previous state
  if ((buttonState2 != lastButtonState2)  && (millis() > 3000))
  {
    // if the state has changed,
    if (buttonState2 == HIGH)
    {
      // if the current state is HIGH then the button
      // wend from off to on
     
      //Here the programm personnalise the announcement for 3 category : the first day, the second, more than 2
      Serial.println("");
      Serial.println("-----");
      if (day == 0)
      {
        Serial.print("Compteur du premier jour (jour actuel):  ");
        Serial.print(buttonPushCounter);
        Serial.println("");
      }
      else if (day == 1)
      {
        Serial.println("Compteur d'hier et d'aujourd'hui :  ");
        Serial.print("- Hier :  ");
        Serial.println(round(counterByDay[1]));
        Serial.print("- Depuis ce matin :  ");
        Serial.println(buttonPushCounter);
      }
      else //this explains that there are a lot of day
      {
        Serial.print("Compteur ");
        Serial.print(day);
        Serial.println(" derniers jours: ");
       
        //listing all days with an array
        for (i = 1; i < (day+1); i = i + 1)
        {
          Serial.print("- Jour ");
          Serial.print(i);
          Serial.print(" :  ");
          Serial.println(round(counterByDay[i])); //round could be delete
        }
       
        Serial.print("- Depuis ce matin :  ");
        Serial.println(buttonPushCounter);
      }
      Serial.println("-----");
      Serial.println("");
    }
  }
  // save the current state as the last state,
  //for next time through the loop
  lastButtonState2 = buttonState2;
 
 
  if (stringComplete)
  {
    //if readString is a number, show the counter of this day
    Serial.println("");
    Serial.println("-----");
    if (isDigit(readString))
    {
      numberWanted = (readString - '0');
     
      Serial.print("Le nombre de basculement du jour ");
      Serial.print(numberWanted);
      Serial.print(" est : ");
      Serial.println(round(counterByDay[numberWanted]));
    }
    else //command unknow
    {
      Serial.println("Ceci n'est as un nombre.");
    }
    Serial.println("-----");
    Serial.println("");
   
    //inizialise string;
    readString = 0;
    stringComplete = false;
  }
}

//Now, what prog must do if commands are sent
void serialEvent()
{
  //creation of the string
  while (Serial.available())
  {
    delay(10); 
    char c = Serial.read();
    readString += c;
   
    charAvailable = Serial.available();
    if (charAvailable == 0)
    {
      stringComplete = true;
    }
  }
}

I'm a new user and I must learn quickly because I'm working on a project baccalaureate, sorry if I made strange mistakes 

Finally, I reorganized my code as in the example of the doc, it seems cleaner:

Code:

//Prepare control by console
int numberWanted;
char readString;
boolean stringComplete = false;
int charAvailable;


void setup()
{
Serial.begin(9600);
}

void loop()
{
  [......]
  if (stringComplete)
  {
    //if readString is a number, show the counter of this day
    if (isDigit(readString))
    {
      numberWanted = (readString - '0');
      
      Serial.print("Le nombre de basculement du jour ");
      Serial.print(numberWanted);
      Serial.print(" est : ");
      Serial.println(round(counterByDay[numberWanted]));
    }
    else //command unknow
    {
      Serial.println("Ceci n'est as un nombre.");
    }
    
    //inizialise string;
    readString = 0;
    stringComplete = false;
  }
}

//Now, what prog must do if commands are sent
void serialEvent()
{
  //creation of the string
  while (Serial.available())
  {
    delay(10);  
    char c = Serial.read();
    readString += c;
    
    charAvailable = Serial.available();
    if (charAvailable == 0)
    {
      stringComplete = true;
    }
  }
}

I show the trick "numberWanted = (readString - '0');" to convert readString in a number. That's not possible ?

Also, I tried

Code:

   charAvailable = Serial.available();
    if (c == \0)
    {
      stringComplete = true;
    }

but it didn't work, why ?

I took the code this morning, here is what I did :

Code:

void serialEvent()
{

  while (Serial.available()) {
    delay(10); 
    char c = Serial.read();
    readString += c;
  }
  Serial.println("");
  Serial.println("-----");
  if (isDigit(readString))
  {
    numberWanted = (readString - '0');
   
    Serial.print("Pushes number of the day ");
    Serial.print(numberWanted);
    Serial.print(" is : ");
    Serial.println(round(counterByDay[numberWanted]));
  }
  else
  {
    Serial.println("This is not a number.");
  }
  Serial.println("-----");
  Serial.println("");
 
  readString = 0;
}

But now, I realize that I have errors in the rest of the program, and I doubt that it comes from this last piece.
Every day I record the number of pulses and I stock it all in a table, here is my method of storage:

Code:

//actualise time
  time = millis();
 
  //preparing time to verify that is a multiple of one day, a day = 15000 ms (to test
  time = time/(round(time / 15000));
 
  //if time = one day, save the number
  if ((time >= 15000) && (time <= 15100) && (numberSaving == 0) && (millis() > 3000))
  {
    //operations to save the number with the date in an array:
    day++;
    counterByDay[day] = buttonPushCounter;
   
    //initialise counter
    buttonPushCounter = 0;
   
    numberSaving = 1;
  }
  //If the number have been saved, and if won't be save a second time, we initialise numberSaving
  else if (((time < 15000) || (time > 15100)) && (numberSaving == 1))
  {
    numberSaving = 0;
  }

If I don't have problem on that 2 parts, I'll show you how I write on the screen.

See you and thank you 

Thanks you so much zoomkat, now I understand ! I will adapt it

I don't really know how string works, it's true. But this mistakes comes from my copy / paste.

I add
char* message;

but I don't know how I can correct
message = message, messageString;

it is
message = message + messageString;

or
message = message . messageString;

?

Hello !
I'm a new french Arduino adept therefore please forget my mistakes 

I'm working for a system which will be control by Serial commands. I must retrieve the command that I entered on the console.
Example :
I write "on" and Arduino light the led.

But it is a real headache...
That's what I've done and that doesn't work:

Code:

int character_available = 0;
char character;

int i = 0;

void setup()
{
  Serial.begin(9600);
}
void loop()
{
}


void serialEvent() //declaration of interrupt function on the serial port
{
  character_available = Serial.available(); // variable containing the number of characters available in the buffer
 
  char messageString[character_available]; //array will contain this message
 
  i = 0;
 
  while(character_available > 0) // so long there are characters to read
  {
    character = Serial.read();
    messageString[i] = character;
    character_available = Serial.available();
    i++;
   
    message = message, messageString[i]; //this must register the string and if we do Serial.print(message); it show "Hello" for example
  }
}

It's getting later in France. Maybe I made ​​a mistake beast... But thanks you and see you soon