Getting address of a char array using pointer

Projects Programming
1

Hello, before posting this, i have searched on this forum a solution to the problem i have. Unlucky, i haven't found yet.

Why i am here? Why do i need? Of course, it's your help on the next thing.

I am creating a char variable with 5 position like this: "char t[4];". Next, i'm assigning char values in each index of the variable. Then, i am creating a pointer variable to save the direction of the first element of t. Finally, i want to check the address but it gave me an error like this: "cannot convert 'char*' to 'int*' in assignment". I think, i'm doing bad assigments but not really sure.

My question is: ¿How can i get the address of a char array?

Gonna post the code above.

Thanks for your attention.

void loop() {
  char t[4];
  t[0] = '3';
  t[1] = '4';
  t[2] = '.';
  t[3] = '1';
  t[4] = '5';
  int* ptr_t;
  ptr_t = &t[0];
  Serial.print("La direccion del apuntador es: ");
  Serial.println(ptr_t);
delay(2000);
}
2

A pointer to the first element of t is t, but it is a char pointer, not an int pointer.

3

Would be so kind if you can write how to print correctly the address.

Thanks

4

Why not cast the pointer to an int, and print the value of the int?

5

void * is the generic pointer type, use that instead of the int *.

Also char t[4] only creates an array of length 4, with elements 0,1,2 and 3. You want a length of 5 if you want t[4] to exist.

6

If you want to print a character array (as a "C-string"), the last element of t[] must contain 0 as a string terminator.

Then use:

Serial.print(t);
7

Hello, i already solved the problem taking account your advices.

My initial problem wasn't the one i posted at the beginning. It was a part of the problem. But i'm gonna explain it above.

I'm sending char character trough I2C between Arduino Nano & ESP8266EX (Nodemcu). Nodemcu works as master and Nano as slave. Nano is getting a float temperature value and Nodemcu ask for the value sending a command, once received the command i turn the value into a char array with dtostrf function and i send it with Wire.write(value) byte to byte. After, Nodemcu has to reconstruct the value saving each byte readed in a local array. The real problem was that garbage was being printed in data received.

As i said, taking account your advices i could fix the problem. Maybe is not the best solution but i'm gonna post the function which gets a string value from I2C without getting garbage.

char arreglo[5];

void getValue(byte slave_address, int Tsen, char* arreglo){
char* str = (char*)malloc(5sizeof(char));
Wire.beginTransmission(slave_address);
Wire.write (Tsen);
Wire.endTransmission();
delay(300);
Wire.requestFrom(slave_address, 5); // request 5 bytes from slave device #1
int i=0;
while(Wire.available())
{
str=Wire.read();*
arreglo = str*;*
* i=i+1;*
* }*
* Serial.print("Transmited Value: ");*
* Serial.println(arreglo);*
* free(str);*
* }*

8

Please remember to use code tags when posting code.

I don't understand why you bother malloc-ind and then free-ing an intermediate buffer.