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I am reading some text from another process through a pipe. The pipe returns the data to the variable chBuf but contains lots of non-printable chars. I tried to remove these non-printable characters using erase and remove but throws an exception. The program works without this erase remove line. What may I doing wrong?

 ReadFile(si->child_out_r, chBuf, BUFSIZE, &dwRead, NULL);
 string s(chBuf);
 s.erase(remove_if(s.begin(), s.end(), [](char c) { return !isprint((unsigned)c); }), s.end());
 cout << s;
ark1974
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    If `chBuf` isn't null-terminated, you're in for a rough time. – user4581301 Jul 20 '21 at 05:40
  • Also, if nulls appear in your data (not at the end of the string) you won't be cleaning the part of the data after the first null. – Dave M. Jul 20 '21 at 05:42
  • @Dave any solution? I don't want it to throw. Should I truncate the string at the first occurrence of null char? – ark1974 Jul 20 '21 at 05:43
  • You could use the `string` constructor that takes the length: `string s(chBuf, dwRead);` Now `s` may contain nulls, and it will have all the data in it. ANd your cleaning process should work too. Another option is to use `vector s(chBuf, dwRead);`. – Dave M. Jul 20 '21 at 05:48
  • @Dave: `string s(chBuf, dwRead);` works like charm. Can you post t as answer? So that I can close the case. Thanks – ark1974 Jul 20 '21 at 05:50

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If the data in your file may contain nulls (amidst other characters that you're interested in), or it is not guaranteed to have a null at the very end, then you need to tell std::string how much data it should use to build the string. You do this with the std::string( const char *, size_t ) constructor:

std::string  s( chBuf, dwRead );

The string cleaning process should work OK if you do that.

Dave M.
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