How do you construct a std::string with an embedded null?

by

Since C++14

we have been able to create literal std::string

#include <iostream>
#include <string>

int main()
{
    using namespace std::string_literals;

    std::string s = "pl-\0-op"s;    // <- Notice the "s" at the end
                                    // This is a std::string literal not
                                    // a C-String literal.
    std::cout << s << "\n";
}

Before C++14

The problem is the std::string constructor that takes a const char* assumes the input is a C-string. C-strings are \0 terminated and thus parsing stops when it reaches the \0 character.

To compensate for this, you need to use the constructor that builds the string from a char array (not a C-String). This takes two parameters – a pointer to the array and a length:

std::string   x("pq\0rs");   // Two characters because input assumed to be C-String
std::string   x("pq\0rs",5); // 5 Characters as the input is now a char array with 5 characters.

Note: C++ std::string is NOT \0-terminated (as suggested in other posts). However, you can extract a pointer to an internal buffer that contains a C-String with the method c_str().

Also check out Doug T’s answer below about using a vector<char>.

Also check out RiaD for a C++14 solution.

More Related Contents:

  1. For loop with pointers and a terminating null
  2. What it is the meaning of this error: conversion from ‘char* [40] to non-scalar type ‘std::string
  3. Converting std::string from const_iterator to char*?
  4. How to trim a std::string?
  5. std::string formatting like sprintf
  6. How to replace all occurrences of a character in string?
  7. Legality of COW std::string implementation in C++11
  8. determine size of array if passed to function
  9. Testing pointers for validity (C/C++)
  10. Alternative to itoa() for converting integer to string C++? [duplicate]
  11. How to concatenate a std::string and an int
  12. Does std::string have a null terminator?
  13. C++ standard: dereferencing NULL pointer to get a reference? [duplicate]
  14. Is null reference possible?
  15. What are the advantages of using nullptr?
  16. Checking if this is null
  17. Checking for NULL pointer in C/C++ [closed]
  18. std::string::c_str() and temporaries
  19. In either C or C++, should I check pointer parameters against NULL/nullptr?
  20. Is std::string ref-counted in GCC 4.x / C++11?
  21. Can a std::string contain embedded nulls?
  22. What does string::npos mean in this code?
  23. Why don’t the std::fstream classes take a std::string?
  24. I want to convert std::string into a const wchar_t *
  25. convert a char* to std::string
  26. Explicit copy constructor
  27. At what point does dereferencing the null pointer become undefined behavior?
  28. C++: how to get fprintf results as a std::string w/o sprintf
  29. Is there a null std::ostream implementation in C++ or libraries?
  30. Append int to std::string

Leave a Comment