How to concatenate bit by bit in c? - c

Question

I have matrix of '1' and '0' with the dimensions 8x8. I need to store the whole matrix in one unsigned long long variable bit by bit. How can i do that?
For example, let's take the matrix of '1' and '0' that is 2x2:
The matrix 2x2:
1 0
0 1
The variable must contain: 1001 in bits.
The same example, but over the matrix 8x8 and unsigned long long variable.
That's what i've tried to do:
#include <stdio.h>
int main()
{
unsigned long long result = 0;
char matrix[8][8]; // lets that the matrix is already filled by '1' and '0'
for (i=0; i<SIZE; i++)
{
for (j=0; j<SIZE; j++)
{
result = result | ((unsigned long long)(matrix[i][j] - '0'));
result <<= 1;
}
}
return 0;
}
Is it right? I implemented this nested loop in my algorithm and that didn't work properly.

Answer 1

Converting the text representation of an integer into its integer value can be done using strtoull().
char buf[sizeof(matrix)+1];
memcpy(buf, matrix, sizeof(matrix));
buf[sizeof(matrix)] = '\0';
result = strtoull(buf, NULL, 2);

Answer 2

try this
const int mx_size = 8;
int main() {
unsigned long long result = 0;
bool matrix[8][8]; // lets that the matrix is already filled by '1' and '0'
for (int i =0; i < mx_size; ++i)
matrix[i][i] = 1;
for (int i = 0; i < mx_size; i++) {
for (int j = 0; j < mx_size; j++) {
result |= (unsigned long long)matrix[i][j] << (i*mx_size + j);
}
}
return 0;
}

Answer 3

Here you have the code (a bit more
#include <stdio.h>
#include <stdint.h>
uint64_t convert(char matrix[8][8], int order, char zero)
{
uint8_t byte;
uint64_t result = 0;
for(size_t row = 0; row < 8; row++)
{
byte = 0;
for(size_t column = 0; column < 8; column++)
{
byte <<= 1;
byte |= matrix[row][column] != zero ? 1 : 0; //anything != defined zero char is 1
}
if (order)
{
result |= (uint64_t)byte << (8 * row);
}
else
{
result |= (uint64_t)byte << (56 - 8 * row);
}
}
return result;
}
int main(void) {
char matrix[8][8] =
{
{'1','0','1','0','1','0','1','0'},
{'0','1','0','1','0','1','0','1'},
{'1','1','1','0','0','0','1','1'},
{'0','0','0','1','1','1','0','0'},
{'1','1','1','1','1','0','0','0'},
{'0','0','0','0','1','1','1','1'},
{'1','1','0','0','1','1','0','0'},
{'0','0','1','1','0','0','1','1'},
};
unsigned long long result = convert(matrix, 0, '0');
for(size_t index = 0; index < 64; index ++)
printf("%1d", !!(result & (1ULL << index)));
printf("\n");
result = convert(matrix,1, '0');
for(size_t index = 0; index < 64; index ++)
printf("%1d", !!(result & (1ULL << index)));
printf("\n");
return 0;
}