Read 8 Bit Binary Numbers from text File in C - c

Question

I'm trying to read from a text file in C that contains a list of 8 bit binary numbers to be used in another function.
The text file is formatted like:
01101101
10110110
10101101
01001111
11010010
00010111
00101011
Ect. . .
Heres kinda what i was trying to do
Pseudo code
void bincalc(char 8_bit_num){
//does stuff
}
int main()
{
FILE* f = fopen("test.txt", "r");
int n = 0, i = 0;
while( fscanf(f, "%d ", &n) > 0 ) // parse %d followed by a new line or space
{
bincalc(n);
}
fclose(f);
}
I think i'm on the right track, however any help is appreciated.

Answer 1

This is not the standard track to do it, but it ok. You are scanning the file reading ints so it will read the string and interpret them as decimal number, which you should in turn convert to the corresponding binary, i.e. converting 1010 decimal to 2^3+2^1=9 decimal. This is of course possible, you just need to transform powers of ten to powers of 2 (1.10^3+0.10^2+1.10^1+0.10^0 to 1.2^3+0.2^2+1.2^1+0.2^0). Be careful that this work with 8-bits numbers, but not with too huge ones (16-bits will not).
The more common way is to read the strings and decode the strings directly, or read char by char and make an incremental conversion.

Answer 2

If you want to have a number at the end, I would suggest something like the following:
int i;
char buf[10], val;
FILE* f = fopen("test.txt", "r");
while( ! feof(f) ) {
val = 0;
fscanf(f, "%s", buf);
for( i=0; i<8; i++ )
val = (val << 1) | (buf[i]-48);
/* val is a 8 bit number now representing the binary digits */
bincalc(val);
}
fclose(f);
This is just a short snippet to illustrate the idea and does not catch all corner cases regarding the file or buffer handling. I hope it will help anyway.

Answer 3

I think this is a possible solution, i made it simple so you can understand and adapt to your needs. You only need to repeat this for each line.
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
FILE *file =fopen("data","r");
char *result=calloc(1,sizeof(char));
char line[8];
int i=0;
for(;i<8;i++)
{
char get = (char)getc(file);
if(get == '0')
*result <<= 1;
else if(get == '1')
*result = ((*result<<1)|0x1) ;
}
printf("->%c\n",*result);
return 0;
}

Answer 4

I don't know of a way to specify binary format for fscanf() but you can convert a binary string like this.
#include <stdio.h>
#include <stdlib.h>
void fatal(char *msg) {
printf("%s\n", msg);
exit (1);
}
unsigned binstr2int(char *str) {
int i = 0;
while (*str != '\0' && *str != '\n') { // string term or newline?
if (*str != '0' && *str != '1') // binary digit?
fatal ("Not a binary digit\n");
i = i * 2 + (*str++ & 1);
}
return i;
}
int main(void) {
unsigned x;
char inp[100];
FILE *fp;
if ((fp = fopen("test.txt", "r")) == NULL)
fatal("Unable to open file");
while (fgets(inp, 99, fp) != NULL) {
x = binstr2int(inp);
printf ("%X\n", x);
}
fclose (fp);
return 0;
}
File input
01101101
10110110
10101101
01001111
11010010
00010111
00101011
Program output
6D
B6
AD
4F
D2
17
2B

Answer 5

Read the file line by line, then use strtol() with base 2.
Or, if the file is guaranteed to be not long, you could also read the full contents in (dynamically allocated) memory and use the endptr parameter.