[Solved] Printng pointer address

Projects Programming
1

Hi,

Why line:
Serial.println(&number);
produces an error when compiling IDE arduino,

and the line compiles correctly:
Serial.println(int(&number));

if the address of a memory is int .

In C++ (W3schools.com) it works without having to qualify the
variable as int?

Thanks everyone for the help.

void setup() {
  Serial.begin(115200);
  delay(10);
  String number = "Pizza";
  
  Serial.println(int(&number));
  Serial.println(&number);
}

void loop() {
}

W3Schools C++

string food = "Pizza";  // A food variable of type string
string* ptr = &food;    // A pointer variable, with the name ptr, that stores the address of food

cout << &food << "\n";
2

C/C++ on Arduino takes on a little different flavor because of the way the IDE does pre-processing of the .ino files and automatic function declarations.

A better place (examples) to learn about Arduino and pointers...

The Basics of C on an Arduino Part 3 Pointers and Arrays (digikey.com)

3

Hi,
thanks for your answer.

PS:
Why does it give error with arduino IDE does not give error with a C++ compiler?

4

I get it, but while you can write "sketches" in C++, Arduino abstracts a lots of concepts:
Arduino Reference - Arduino Reference

Once you learn C++ you can apply it to Arduino rather easily, but if you know Arduino you do not know C/C++.

A rather bad association: if you know BASIC you do not know assembler, but if you know assembler, you know BASIC.

5

Tks

6

print() is overloaded to handle different types. It simply lacks an overload to print pointers to an int.

size_t print(const __FlashStringHelper *);
    size_t print(const String &);
    size_t print(const char[]);
    size_t print(char);
    size_t print(unsigned char, int = DEC);
    size_t print(int, int = DEC);
    size_t print(unsigned int, int = DEC);
    size_t print(long, int = DEC);
    size_t print(unsigned long, int = DEC);
    size_t print(double, int = 2);
    size_t print(const Printable&);

    size_t println(const __FlashStringHelper *);
    size_t println(const String &s);
    size_t println(const char[]);
    size_t println(char);
    size_t println(unsigned char, int = DEC);
    size_t println(int, int = DEC);
    size_t println(unsigned int, int = DEC);
    size_t println(long, int = DEC);
    size_t println(unsigned long, int = DEC);
    size_t println(double, int = 2);
    size_t println(const Printable&);
    size_t println(void);
3 Likes
7

As long as you're learning C++ ..... the preferred "C++ way" would be:

 Serial.println(reinterpret_cast<intptr_t>(&number));
1 Like
8

Hi,
I'm a young man born in the late 40's trying to improve the knowledge of C++ and "C Arduino".

Thank you all for your help.

9

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