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POWhy is there no std::string constructor for reference to array?
 

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  1. POWhy is there no std::string constructor for reference to array?
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    <p>String literals are array objects:</p> <pre class="lang-c prettyprint-override"><code>typeid("hello").name() // char [6] </code></pre> <p>This seems convenient because the size of the string literal (=array) is known at compile time. So why is there no constructor to <code>std::string</code> that takes a reference to an array?</p> <pre class="lang-c prettyprint-override"><code>// this would be great template &lt;int N&gt; std::string(const char (&amp; array)[N]); </code></pre> <p>Instead there are constructors that take <code>const char * s</code>, <code>const char * s, size_t n</code> or two <code>InputIterator</code>s (eg. <code>const char * begin, const char * end</code>). All of these have drawbacks; the array is implicitly converted to a pointer and the size information is lost, so various methods are used to get it back. Working, but increasingly crazy examples:</p> <pre class="lang-c prettyprint-override"><code>// std::string(const char * s) version: std::string s1("hello"); // calls std::strlen(s) internally // std::string(const char * s, size_t n) version: std::string s2("hello", 5); // programmer does std::strlen(s) mentally std::string s3("hello", sizeof("hello")); // have to repeat string literal // macro helper to avoid repeating string literal (ugly and dangerous) #define STRLIT(x) std::string(x, sizeof(x)); // could be a function I guess std::string s4 = STRLIT("hello"); // not much improvement (and macros are evil) // std::string(InputIterator begin, InputIterator end) version: char tmp[] = "hello"; // copy array std::string s5(&amp;tmp[0], &amp;tmp[sizeof(tmp)]); // so you can reference it twice // or trust the compiler to return the same address for both literals std::string s6(&amp;"hello"[0], &amp;"hello"[sizeof("hello")]); // totally crazy </code></pre>
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    1. USAnders Johansson
    1. USAnders Johansson
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    1. COYou can always write your own `make_string` function which does this.
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      1. POWhy is there no std::string constructor for reference to array?
      1. USPubby
    2. COfyi the `sizeof` catches the null byte and returns 6.
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      1. POWhy is there no std::string constructor for reference to array?
      1. USdjechlin
    3. CO`STRLIT` can be an inline function rather than a macro. `tmeplate<int len> std::string strlit(const char(&str)[len]) {return std::string(str,len);}` (this is also what Pubby suggests)
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      1. POWhy is there no std::string constructor for reference to array?
      1. USMooing Duck
 

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