Hello, can somebody explain the difference between cast and conversion, please?
cast e.g. int x; float y; y = (float) x;
conversion e.g. int x; float y; y = float(x);
Thank you 
Hello, can somebody explain the difference between cast and conversion, please?
The "conversion" is creating a float from the value in the parentheses. Since you have not given x a value, you haven't a clue what will be in y.
The cast is telling the compiler to treat some number of bytes (4 in the case of a float cast) as though they were a float. The first byte is the first byte of the variable x. The second byte is the second half of x. The 3rd and 4th bytes are whatever bytes follow x in memory.
The result of that cast will be garbage in y, too.
Ok, thank you.
Can you give some examples where i have to use conversion and where i have to use cast, please?
PaulS:
The cast is telling the compiler to treat some number of bytes (4 in the case of a float cast) as though they were a float. The first byte is the first byte of the variable x. The second byte is the second half of x. The 3rd and 4th bytes are whatever bytes follow x in memory.
That is only true for pointers to float / int.
Functional there should be no difference in value between (float)x and float(x).
int x = 1234;
void setup() {
Serial.begin(250000);
float y = (float)x;
Serial.print(F("(float)x = "));
Serial.println(y);
y = float(x);
Serial.print(F("float(x) = "));
Serial.println(y);
y = *((float*)&x);
Serial.print(F("*((float*)&x) = "));
Serial.println(y);
}
void loop() {}
(float)x = 1234.00
float(x) = 1234.00
*((float*)&x) = 0.00
Can you give some examples where i have to use conversion and where i have to use cast, please?
You NEVER have to use "conversion".
float y = 1234;
does EXACTLY the same thing as
float y = float(1234);
You rarely need to cast one type to another, unless the types are pointers. When you DO need to cast, you'll know it, and know what cast is required.
Whandall:
Functional there should be no difference in value between (float)x and float(x).
Exactly!
void setup()
{
Serial.begin(9600);
int x = 1234;
float y;
y = (float)x;
Serial.println(y); //shows: 1234.00
long *p;
p = (long*) &y;
long m = *p;
Serial.println(m, HEX); //shows: binary32 formatted value 449A4000
Serial.println("//--------------------------------");
float y1;
y1 = float(x);
Serial.println(y1); //shows: 1234.00
long *p1;
p1 = (long*) &y1;
long m1 = *p1;
Serial.println(m1, HEX); //shows: binary32 formatted value 449A4000
}
void loop()
{
}