Begin Arduino by C

Using Arduino Programming Questions
1

Hello, some body can help to correct error as follow C code (4 digit of 7 segment):

----------------------C code ----------------------------------------
const int numeral[10] = {
//ABCDEFG /dp
B11111100, // 0
B01100000, // 1
B11011010, // 2
B11110010, // 3
B01100110, // 4
B10110110, // 5
B00111110, // 6
B11100000, // 7
B11111110, // 8
B11100110, // 9
};
// pins for decimal point and each segment
// DP, G, F, E, D, C, B, A
const int segmentPins[ ] = { 13, 8, 7, 6, 5, 4, 3, 2 };
const int nbrDigits= 4; // the number of digits in the LED display
//dig 0 1 2 3
const int digitPins[ nbrDigits] = { 9, 10, 11, 12 };

void setup()
{
for(int i=0; i < 8; i++) {
pinMode(segmentPins[ i] , OUTPUT); // set segment and DP pins to output
}
for (int i=0; i < nbrDigits; i++) {
pinMode(digitPins[ i] , OUTPUT);
}
}

void loop()
{
int value = analogRead(0);
showNumber(value);
}

void showNumber( int number)
{
if(number == 0) {
showDigit( 0, nbrDigits‐1); // display 0 in the rightmost digit
} else {
// display the value corresponding to each digit
// leftmost digit is 0, rightmost is one less than the number of places
for (int digit = nbrDigits‐1; digit >= 0; digit‐‐) {
if(number > 0) {
showDigit( number % 10, digit);
number = number / 10;
}
}
}
}

// Displays given number on a 7‐segment display at the given digit position
void showDigit( int number, int digit)
{
digitalWrite( digitPins[ digit] , HIGH );
for(int segment = 1; segment < 8; segment++) {
boolean isBitSet = bitRead(numeral[ number] , segment);
// isBitSet will be true if given bit is 1
// isBitSet = ! isBitSet; // Code Option*
// uncomment the above Code Option line for common anode display
digitalWrite( segmentPins[ segment] , isBitSet);
}
delay(5);
digitalWrite( digitPins[ digit] , LOW );
}

---------------------------error messages-------------------------

Arduino: 1.6.6 (Windows 7), Board: "Arduino Nano, ATmega328"

_7Segment_x_4_Nano_1:41: error: stray '\342' in program

showDigit( 0, nbrDigits�1); // display 0 in the rightmost digit

^

_7Segment_x_4_Nano_1:41: error: stray '\200' in program

_7Segment_x_4_Nano_1:41: error: stray '\220' in program

_7Segment_x_4_Nano_1:45: error: stray '\342' in program

for (int digit = nbrDigits�1; digit >= 0; digit��) {

^

_7Segment_x_4_Nano_1:45: error: stray '\200' in program

_7Segment_x_4_Nano_1:45: error: stray '\220' in program

_7Segment_x_4_Nano_1:45: error: stray '\342' in program

_7Segment_x_4_Nano_1:45: error: stray '\200' in program

_7Segment_x_4_Nano_1:45: error: stray '\220' in program

_7Segment_x_4_Nano_1:45: error: stray '\342' in program

_7Segment_x_4_Nano_1:45: error: stray '\200' in program

_7Segment_x_4_Nano_1:45: error: stray '\220' in program

Z:\D\TECH MANUAL BOOKS\1_TU SACH VI XU LY\Arduino\Proteus file cho Arduino UNO_7Segment_x_4_Nano_1_7Segment_x_4_Nano_1.ino: In function 'void showNumber(int)':

_7Segment_x_4_Nano_1:41: error: expected ')' before numeric constant

showDigit( 0, nbrDigits�1); // display 0 in the rightmost digit

^

_7Segment_x_4_Nano_1:45: error: expected ';' before numeric constant

for (int digit = nbrDigits�1; digit >= 0; digit��) {

^

_7Segment_x_4_Nano_1:45: error: expected ')' before ';' token

for (int digit = nbrDigits�1; digit >= 0; digit��) {

^

_7Segment_x_4_Nano_1:45: error: 'digit' was not declared in this scope

for (int digit = nbrDigits�1; digit >= 0; digit��) {

^

_7Segment_x_4_Nano_1:45: error: expected ';' before ')' token

for (int digit = nbrDigits�1; digit >= 0; digit��) {

^

_7Segment_x_4_Nano_1:67: error: expected '}' at end of input

}

^

_7Segment_x_4_Nano_1:67: error: expected '}' at end of input

exit status 1
stray '\342' in program

This report would have more information with
"Show verbose output during compilation"
enabled in File > Preferences.

arduino C code question_1.pdf (86.7 KB)

2

The problem is with your minus signs in the 'showNumber()' function.

This:-

showDigit( 0, nbrDigits‐1); // display 0 in the rightmost digit

should look like this:-

showDigit( 0, nbrDigits-1); // display 0 in the rightmost digit

And this:-

for (int digit = nbrDigits‐1; digit >= 0; digit‐‐)

should look like this:-

for (int digit = nbrDigits-1; digit >= 0; digit--)

(This was tricky to find.)
Edit: I just noticed that they look identical above, but they look slightly different in the IDE.
Here's a screenshot from my IDE/editor:-
Bad editor font.JPG

This compiles fine:-

const int numeral[10] =
{
    //ABCDEFG /dp
    B11111100, // 0
    B01100000, // 1
    B11011010, // 2
    B11110010, // 3
    B01100110, // 4
    B10110110, // 5
    B00111110, // 6
    B11100000, // 7
    B11111110, // 8
    B11100110, // 9
};
// pins for decimal point and each segment
// DP, G, F, E, D, C, B, A
const int segmentPins[ ] = { 13, 8, 7, 6, 5, 4, 3, 2 };
const int nbrDigits = 4; // the number of digits in the LED display
//dig 0 1 2 3
const int digitPins[ nbrDigits] = { 9, 10, 11, 12 };

void setup()
{
    for (int i = 0; i < 8; i++)
    {
        pinMode(segmentPins[ i] , OUTPUT); // set segment and DP pins to output
    }
    for (int i = 0; i < nbrDigits; i++)
    {
        pinMode(digitPins[ i] , OUTPUT);
    }
}

void loop()
{
    int value = analogRead(0);
    showNumber(value);
}

void showNumber( int number)
{
    if (number == 0)
    {
        showDigit( 0, nbrDigits-1); // display 0 in the rightmost digit // ***
    }
    else
    {
        // display the value corresponding to each digit
        // leftmost digit is 0, rightmost is one less than the number of places
        for (int digit = nbrDigits-1; digit >= 0; digit--)  // ***
        {
            if (number > 0)
            {
                showDigit( number % 10, digit);
                number = number / 10;
            }
        }
    }
}

// Displays given number on a 7‐segment display at the given digit position
void showDigit( int number, int digit)
{
    digitalWrite( digitPins[ digit] , HIGH );
    for (int segment = 1; segment < 8; segment++)
    {
        boolean isBitSet = bitRead(numeral[ number] , segment);
        // isBitSet will be true if given bit is 1
        // isBitSet = ! isBitSet; // Code Option*
        // uncomment the above Code Option line for common anode display
        digitalWrite( segmentPins[ segment] , isBitSet);
    }
    delay(5);
    digitalWrite( digitPins[ digit] , LOW );
}

Edit: Oh, and in future, please post your code and any error messages between code tags, not inline. Code tags are generated using the </> button in the edit window.

3

At a guess you copied the code from a Web page which has included some Unicode characters as Steve has demonstrated. Fix the problems that he has pointed out and let us know how you get on.

4

I just begin with C. so I had copy that code from website.

Thank you very much.

5

VuongBec:
I just begin with C. so I had copy that code from website.

Thank you very much.

Many websites that contain code offer the facility to download a file containing the code or an option to display the "raw" version of the code, both of which get round the problem.

As a matter of interest can you please provide a link to the page that you got the code from ?