Make IsHex use string_view

Author: sipa

src/util/strencodings.cpp

@@ -58,12 +58,10 @@ signed char HexDigit(char c)
     return p_util_hexdigit[(unsigned char)c];
 }
 
-bool IsHex(const std::string& str)
+bool IsHex(std::string_view str)
 {
-    for(std::string::const_iterator it(str.begin()); it != str.end(); ++it)
-    {
-        if (HexDigit(*it) < 0)
-            return false;
+    for (char c : str) {
+        if (HexDigit(c) < 0) return false;
     }
     return (str.size() > 0) && (str.size()%2 == 0);
 }

src/util/strencodings.h

@@ -59,7 +59,7 @@ std::vector<unsigned char> ParseHex(std::string_view str);
 signed char HexDigit(char c);
 /* Returns true if each character in str is a hex character, and has an even
  * number of hex digits.*/
-bool IsHex(const std::string& str);
+bool IsHex(std::string_view str);
 /**
 * Return true if the string is a hex number, optionally prefixed with "0x"
 */