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binary input
Mar 31, 2017 at 12:56am
I have a binary string for input, for example 0110011, the input is being read left to right one at a time; in the ASCII chart decimal 48 is ASCII 0, and 49 is ASCII 1; how would putting each character of the input through this snippet of code as it is being read affect the input: (i=ch -'0') in words i equals char minus zero getchar is getting the input.
Mar 31, 2017 at 1:46am
yes, you can get the value of the digit by peeling it off the ascii table as you said.
or you can just do something like
forceinline char/bool getbindigit(char c)
{
if (c == '1')
return 1; ///or true
return 0; // or false
}
or :? statement to do the same, some say its faster.
note that its not a string after you do this. ascii 0 is end of string, and I don't even know what it does if you print a string with one in the middle of it, with a char array it just stops right there. 1 isn't anything friendly to print either, its some control character. At this point all its good for is turning the binary back into an integer value.
when I was doing embedded C we had a guy with a giant include file of # defines
Ob01100
etc (letter O not zero) that he used and added to when he had a new value. It was horrible, but it worked back then.
or you can just do something like
forceinline char/bool getbindigit(char c)
{
if (c == '1')
return 1; ///or true
return 0; // or false
}
or :? statement to do the same, some say its faster.
note that its not a string after you do this. ascii 0 is end of string, and I don't even know what it does if you print a string with one in the middle of it, with a char array it just stops right there. 1 isn't anything friendly to print either, its some control character. At this point all its good for is turning the binary back into an integer value.
when I was doing embedded C we had a guy with a giant include file of # defines
Ob01100
etc (letter O not zero) that he used and added to when he had a new value. It was horrible, but it worked back then.
Last edited on Mar 31, 2017 at 1:51am
Mar 31, 2017 at 1:59am
thank you for responding!! so if the input is a string of 0's 1's the compiler reads 48 decimal for each 0 and 49 for 1 therefore I have to tell it that I want
it to interpret my 0 and 1 as 0 and 1 and not something else.
it to interpret my 0 and 1 as 0 and 1 and not something else.
Mar 31, 2017 at 2:07am
> in the ASCII chart decimal 48 is ASCII 0, and 49 is ASCII 1
The encoding of the characters in the execution character set is locale specific; it need not (and sometimes does not) correspond to the encoding as specified by ASCII.
However, C++ does guarantee that, no matter what character encoding is in use:
ie. if the value of '0' is 147, then the value of '1' would be 148, the value of '2' would be 149 and so on.
Therefore, if the character ch is a character representing a decimal digit (std::isdigit(ch) is true),
then ch - '0' would give that digit as an integer. '7' - '0' == 7 etc.
The encoding of the characters in the execution character set is locale specific; it need not (and sometimes does not) correspond to the encoding as specified by ASCII.
However, C++ does guarantee that, no matter what character encoding is in use:
| In both the source and execution basic character sets, the value of each character after 0 in the list of decimal digits shall be one greater than the value of the previous. - IS |
ie. if the value of '0' is 147, then the value of '1' would be 148, the value of '2' would be 149 and so on.
Therefore, if the character ch is a character representing a decimal digit (std::isdigit(ch) is true),
then ch - '0' would give that digit as an integer. '7' - '0' == 7 etc.
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