Remove Control Characters out of a string - c++

Question

I have a string given, which contains the following content (so the following lines are stored in a String-variable):
S*⸮
------------------------
K!
NAG 00.10
K"
NMAGICSTAR 2 L V1.0-1
K#
AUFSTELLORT: S 00000000
K$
GERAET NR.: 0000000000
KC
ZULASSUNGS NR.:411107770
K)
BAUART: NAG5A02
K(
ABLAUFDATUM: 2021/04
------------------------
Can anyone help me or give me a short hint how to remove the control codes (so the S*⸮ respectively the K!) out of this string (there is always a small rectangle before the control code, i don't know why it is removed)? So that in the end, it's
------------------------
NAG 00.10
NMAGICSTAR 2 L V1.0-1
AUFSTELLORT: S 00000000
GERAET NR.: 0000000000
ZULASSUNGS NR.:411107770
BAUART: NAG5A02
ABLAUFDATUM: 2021/04
------------------------
Let me finally quote something out of the documentation, maybe it helps:
Each line is max. 24 characters long and must end with LF [0Ah]
Control Code "ESC 'S' 21h LF" means: XON Startsequence with manufacturer code, machine code and dataset code
I am trying to do this whole task on an ESP32/ Arduino IDE (C++).

Answer 1

This is not an anwser. You may use the following code to print you string as integer in hex form. Every 12 characters a wide separation, and every 24 a new line. The arrange makes easier for you to count 24 characters.
#include <iostream>
void dump_str(const std::string&str)
{
int n;
std::cout << std::hex;
for (int i=0; i<str.size(); i++)
{
n = str[i];
if (i%24==0) std::cout << std::endl;
else if (i%12 == 0 ) std::cout <<" ";
if (n<16) std::cout << " " << '0' << n;
else std::cout << " " << n;
}
}
int main ()
{
std::string str ( "some\r\ttest\rst\2\athis is \n a ran\5dom\10g\n\nTake this for granted. To bo or not to be\a\a\t\t");
dump_str(str);
}
Print-out of this example:(meaning of the number can be checked in an ascii table google search.)
73 6f 6d 65 0d 09 74 65 73 74 0d 73 74 02 07 74 68 69 73 20 69 73 20 0a
20 61 20 72 61 6e 05 64 6f 6d 08 67 0a 0a 54 61 6b 65 20 74 68 69 73 20
66 6f 72 20 67 72 61 6e 74 65 64 2e 20 54 6f 20 62 6f 20 6f 72 20 6e 6f
74 20 74 6f 20 62 65 07 07 09 09
Send you string to above function dum_str(string), and copy the resultant table appending to your post.

Answer 2

Here's how to split the string at \r and \n characters. This way you can iterate each line separately.
void str_split(const std::string& in, std::vector<std::string>& out, const std::string& delim=" \t\r\n")
{
std::string::size_type firstPos = in.find_first_not_of(delim);
std::string::size_type secondPos = in.find_first_of(delim, firstPos);
out.clear();
if(firstPos != std::string::npos)
out.push_back( in.substr( firstPos, secondPos - firstPos ) );
while( secondPos != std::string::npos )
{
firstPos = in.find_first_not_of(delim, secondPos);
if(firstPos == std::string::npos)
break;
secondPos = in.find_first_of( delim, firstPos );
out.push_back( in.substr( firstPos, secondPos - firstPos ) );
}
}