Rules for C string literals escape character

Question

What are the rules for the escape character   in string literals  Is there a list of all the characters that are escaped   In particular  when I use   in a string literal in gedit  and follow it by any three numbers  it colors them differently   I was trying to create a std  string constructed from a literal with the character 0 followed by the null character   0   followed by the character 0  However  the syntax highlighting alerted me that maybe this would create something like the character 0 followed by the null character   00  aka  0   which is to say  only two characters   For the solution to just this one problem  is this the best way to do it   std  string   0 0   0   3      String concatenation    And is there some reference for what the escape character does in string literals in general  What is   a   for instance

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With the magic of user-defined literals  we have yet another solution to this  C  14 added a std  string literal operator   using namespace std  string literals  auto const x     0   0 s    Constructs a string of length 2  with a   0  character  null  followed by a  0  character  the digit zero   I am not sure if it is more or less clear than the initializer list lt char gt  constructor approach  but it at least gets rid of the   and   characters

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ascii is a package on linux you could download  for example sudo apt-get install ascii ascii Usage  ascii  -dxohv   -t   char-alias     -t   one-line output  -d   Decimal table  -o   octal table  -x   hex table -h   This help screen -v   version information Prints all aliases of an ASCII character  Args may be chars  C  -escapes  English names   -escapes  ASCII mnemonics  or numerics in decimal octal hex    This code can help you with C C   escape codes like  x0A

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0 will be interpreted as an octal escape sequence if it is followed by other digits  so  00 will be interpreted as a single character    0 is technically an octal escape sequence as well  at least in C    The way you re doing it   std  string   0 0   0   3      String concatenation    works because this version of the constructor takes a char array  if you try to just pass  0 0   0  as a const char   it will treat it as a C string and only copy everything up until the null character   Here is a list of escape sequences

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a is the bell alert character  which on some systems triggers a sound   nnn  represents an arbitrary ASCII character in octal base  However   0 is special in that it represents the null character no matter what   To answer your original question  you could escape your  0  characters as well  as   std  string    060 000 060   3      since an ASCII  0  is 60 in octal   The MSDN documentation has a pretty detailed article on this  as well cppreference

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Control characters    Hex codes assume an ASCII-compatible character encoding      a    x07   alert  bell   b    x08   backspace  t    x09   horizonal tab  n    x0A   newline  or line feed   v    x0B   vertical tab  f    x0C   form feed  r    x0D   carriage return  e    x1B   escape  non-standard GCC extension    Punctuation characters         quotation mark  backslash not required for           apostrophe  backslash not required for           question mark  used to avoid trigraphs       backslash   Numeric character references        up to 3 octal digits  x   any number of hex digits  u   4 hex digits  Unicode BMP  new in C  11   U   8 hex digits  Unicode astral planes  new in C  11     0    00    000   octal ecape for null character  If you do want an actual digit character after a  0  then yes  I recommend string concatenation   Note that the whitespace between the parts of the literal is optional  so you can write   0  0

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I left something like this as a comment  but I feel it probably needs more visibility as none of the answers mention this method   The method I now prefer for initializing a std  string with non-printing characters in general  and embedded null characters in particular  is to use the C  11 feature of initializer lists   std  string const str    0    6     a    H     t       I am not required to perform error-prone manual counting of the number of characters that I am using  so that if later on I want to insert a   013  in the middle somewhere  I can and all of my code will still work  It also completely sidesteps any issues of using the wrong escape sequence by accident   The only downside is all of those extra   and   characters

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