[SOLVED]Only F constant couldn't be known in every procedure scope

Using Arduino Programming Questions
1

I followed instruction how to drive 7 segment with adruino from this link: Make: Projects

Until on Programming Step, a bunch of error happened while I compiled the code. the original code is here: Make-Projects/_7_segment.pde at master · ril3y/Make-Projects · GitHub. But it showed some error, So, I tried to correct the code. here is my code.

#define A 8
#define B 9
#define C 2
#define D 3
#define E 4
#define F 5
#define G 6

void clr()
{
  /*Clears the LED*/
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, HIGH);
  digitalWrite(E, HIGH);
  digitalWrite(F, HIGH);
  digitalWrite(G, HIGH);
}

void char_A()
{
  digitalWrite(D, HIGH);
  digitalWrite(E, LOW);
 //digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
}

void char_B()
{
  //Displays B
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, LOW);
}

void char_C()
{
  //Displays C
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, HIGH);
  digitalWrite(A, LOW);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
}

void char_D()
{
  //Displays D
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, HIGH);
  digitalWrite(G, LOW);
  digitalWrite(A, HIGH);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
}

void char_E()
{
  //Displays E
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
}

void char_F()
{
  //Displays F
  digitalWrite(D, HIGH);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
}

void one()
{
  //Displays 1
  digitalWrite(D, HIGH);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, HIGH);
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
}

void two()
{
  //Displays 2
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, HIGH);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, HIGH);
}

void three()
{
  //Displays 3
  digitalWrite(D, LOW);
  digitalWrite(E, HIGH);
  digitalWrite(F, HIGH);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
}

void four()
{
  //Displays 4
  digitalWrite(D, HIGH);
  digitalWrite(E, HIGH);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, HIGH);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
}

void five()
{
  //Displays 5
  digitalWrite(D, LOW);
  digitalWrite(E, HIGH);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, HIGH);
  digitalWrite(C, LOW);
}

void six()
{
  //Displays 6
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, HIGH);
  digitalWrite(C, LOW);
}

void seven()
{
  //Displays 7
  digitalWrite(D, HIGH);
  digitalWrite(E, HIGH);
  digitalWrite(F, HIGH);
  digitalWrite(G, HIGH);
  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
}

void eight()
{
  //Displays 8
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
}

void nine()
{
  //Displays 9
  digitalWrite(D, LOW);
  digitalWrite(E, HIGH);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
}

void zero()
{
  //Displays 0
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, HIGH);
  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
}

void LoopDisplay()
{
  //Loop through all Chars and Numbers
  char_A();
  delay(1000);
  char_B();
  delay(1000);
  char_C();
  delay(1000);
  char_D();
  delay(1000);
  char_E();
  delay(1000);
  char_F();
  delay(1000);
  one();
  delay(1000);
  two();
  delay(1000);
  three();
  delay(1000);
  four();
  delay(1000);
  five();
  delay(1000);
  six();
  delay(1000);
  seven();
  delay(1000);
  eight();
  delay(1000);
  nine();
  delay(1000);
  zero();
  delay(1000);
}

void setup()
{
  //Setup our pins
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(D, OUTPUT);
  pinMode(E, OUTPUT);
  pinMode(F, OUTPUT);
  pinMode(G, OUTPUT);
  Serial.begin(9600);  //Begin serial communcation

}

void loop()
{
  Serial.println("Starting\n");
  LoopDisplay();
}

And strange error message always appear. here it is.

seven_segment.cpp: In function 'void clr()':
seven_segment:17: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void char_B()':
seven_segment:38: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void char_C()':
seven_segment:50: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void char_D()':
seven_segment:62: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void char_E()':
seven_segment:74: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void char_F()':
seven_segment:86: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void one()':
seven_segment:98: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void two()':
seven_segment:110: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void three()':
seven_segment:122: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void four()':
seven_segment:134: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void five()':
seven_segment:146: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void six()':
seven_segment:158: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void seven()':
seven_segment:170: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void eight()':
seven_segment:182: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void nine()':
seven_segment:194: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void zero()':
seven_segment:206: error: 'F' was not declared in this scope
seven_segment.cpp: In function 'void setup()':
seven_segment:258: error: 'F' was not declared in this scope

See, "F" was not declared in every scope????

Then, I gave comment mark (using "//") on each line which contains "F" constant. Then I compiled and upload it successfully. I assume all pin works properly except pin 5 (which I set comment each "F" code related).

Why F constant couldn't be known in every procedure scope?

2

I using power from my laptop ...

That's not the problem.

Under version 1.0 of the IDE the word "F" is used to indicate a string is in Flash memory. Better choose another one.

3

For example, if you change F to FOO it compiles OK.

4

F is a macro defined by the Arduino environment. Some details are available here...

I suggest using something other than "F" to avoid the conflict; maybe "sF" for "segment F".

5

@CB: ninja by 12 seconds!

6

So, it seems "F" has been one of reserved word in adruino programming environment and I should use another name. suddenly clear the problem. thanks.

7

Argh! Bested by an Aussie! I have a reasonable excuse. I was letting my Australian Terrier outside. She wanted to yell at the neighborhood skunk.