Create std::string from int8_t array

Question

In some code int8_t[] type is used instead of char[].

int8_t title[256] = {'a', 'e', 'w', 's'};
std::string s(title); // compile error: no corresponding constructor

How to properly and safely create a std::string from it?

When I will do cout << s; I want that it print aews, as if char[] type was passed to the constructor.

See this question ... https://stackoverflow.com/questions/42961443/convert-from-uint8-t-to-char-in-c — John Sheridan, Nov 23 '21 at 15:37

Vlad from Moscow · Accepted Answer · 2021-11-23T15:45:55.667

2

Here you are

int8_t title[256] = { 'a', 'e', 'w', 's' };
std::string s( reinterpret_cast<char *>( title ) );
std::cout << s << '\n';

Or you may use also

std::string s( reinterpret_cast<char *>( title ), 4 );

edited Nov 23 '21 at 15:45

answered Nov 23 '21 at 15:38

Vlad from Moscow

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Sounds like a bad idea without an explicit null terminator in the array. – perivesta Nov 23 '21 at 15:40
@dave And why do you have decided that there is no null terminating character? – Vlad from Moscow Nov 23 '21 at 15:40
There should be 252 null terminators in that array. :-) – Ted Lyngmo Nov 23 '21 at 15:41
@dave I though the same thing and then remembered that all missing initializers are set to `0`, so it has 252 null terminators in it. – NathanOliver Nov 23 '21 at 15:41
1

Ah right, didn't see the 256 size. That's ok then in this case – perivesta Nov 23 '21 at 15:42

François Andrieux · Answer 2 · 2021-11-23T15:50:38.313

std::string like other containers can be constructed using a pair of iterators. This constructor will use implicit conversions if available, such as converting int8_t to char.

int8_t title[256] = {'a', 'e', 'w', 's'};
std::string s(std::begin(title), std::end(title));

Note that this solution will copy the whole array, including the unused bytes. If the array is often much larger than it needs to be, you can look for the null terminator instead

int8_t title[256] = {'a', 'e', 'w', 's'};
auto end = std::find(std::begin(title), std::end(title), '\0');
std::string s(std::begin(title), end);

Create std::string from int8_t array

2 Answers2