Bitwise operation

Using Arduino Programming Questions
1

I am working on seven segment display that i pulled off from washing machine.there are many segments .so i diside to make 6*2 2d array for storing 2 byte values (becouse i am having a 2 74hc595) and 6 digits. I want to periodically asigne values like 0b01000001( for number 1) in to 2d array without affecting existing bits if it has 101 and i want to add 010 then i want to result to be 111.
And also i want to remove 010 from resulted 111 value.

2 
byte result = 0b101 | 0b010;          // will produce 0b111

byte result2 = 0b111 & ( ~ 0b010);    // remove 010 from 111
3 
byte result |=  0b001; // to add
byte result &= ~0b010; // to remove
byte result ^=  0b010; // to toggle

identical to

byte result = result |  0b001; // to add
byte result = result & ~0b010; // to remove
byte result = result ^  0b010; // to toggle
4

consider following which i use with a Multifunction Shield

// shift 16-bits from data into the shift register
void output (
    uint16_t  data)
{
    digitalWrite (Latch, LOW);

    for (unsigned i = 0; i < 16; i++, data <<= 1)  {
        digitalWrite (Data, 0 != (data & 0x8000));

        digitalWrite (Clock, HIGH);
        digitalWrite (Clock, LOW);
    }

    digitalWrite (Latch, HIGH);
}
5

Only if you remove the byte type specifiers. The first isn't even valid code with byte since that makes the line a declaration with an initializer, and you can't use operators like |= in an initializer like that. In the second code, it's valid only if result already existed as another variable (in an outer scope) before this line.

6

Actually, it should have been written

byte result = 0bxxxxxxxx;
.
.
.
result |=  0b001; // to add
result &= ~0b010; // to remove
result ^=  0b010; // to toggle
1 Like
7

"add" is a bad word to use here, because addition exists. "set" and "clear" are the usual words for bit operations.

8

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