Break up a string

**cdonlan** · 11-10-2004

OK guys here is my problem. I have an string that consist of 8 bits all 1s and 0s. These strings are scanned in from a text file. I have to take these strings and do severl logic test with them(add,or,nagation,and...) I think I need to save the string as a single characture and do the test with it. What function can i use to scan in a single char off a string and at it to a char that will contain one byte when it is dont.

I believe it is going to involve a for statement, but I dont know what will scan in a single char.

Thanks
Chris

**sean** · 11-10-2004

I think I need to save the string as a single characture and do the test with it

And... what makes you say that? Are you possibly confusing this with pointers, which will look like single chars to the "untrained-observer". Or if you're referring to just having a for loop that looks at one character at the same time, is there a reason that you can't just use

Code:

char c
for(int i = 0; i < string_length; i++)
{
     c = string[i];
     // Tests performed on c
}

**itsme86** · 11-10-2004

I think he means something more like this:

Code:

int main(void)
{
  char str[] = "10011011";
  unsigned char ch = 0;
  int i;

  for(i = 0;str[i];i++)
    if(str[i] == '1')
      ch += 1 << (7-i);

  return 0;
}

And then he can use ch for all of his bit operations.

**Dave_Sinkula** · 11-10-2004

>What function can i use to scan in a single char off a string and at it to a char that will contain one byte when it is dont.

Why not go 8 "bits" at a time and use strtoul with base 2?

Code:

  char str[] = "10011011";
  unsigned char ch = strtoul(str, NULL, 2);

**itsme86** · 11-10-2004

Well sure...if you want to do it the easy way

**gayomard_mehta** · 11-13-2004

in order to scan a single character use getchar() and putchar()
functions in order to split a string use the pointers to the string for more help email me @ [email protected]

always happy to help

**manofsteel972** · 11-13-2004

What about a union?

Code:

union Bitstring
{
    char string[8];
    struct 
    {
        char b1;
        char b2;
        char b3;
        char b4;
        char b5;
        char b6;
        char b7;
        char b8;
    }charbit;
    
};

That will let you treat it as individual bits or as a string. I think I read about this in another post?

**quzah** · 11-13-2004

Why? You can do the same thing with an array:

Code:

char bitsbutnotreally[ size ] = { "10110010" };

bitsbutnotreally[ bitnumber ] = '0';

I suppose a union would work, but I don't see the point in the added complexity. Except of course just because you can.

Quzah.

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