Fix subscript[0] in utilstrencodings.cpp

src/utilstrencodings.cpp

@@ -228,7 +228,7 @@ std::vector<unsigned char> DecodeBase64(const char* p, bool* pfInvalid)
 std::string DecodeBase64(const std::string& str)
 {
     std::vector<unsigned char> vchRet = DecodeBase64(str.c_str());
-    return (vchRet.size() == 0) ? std::string() : std::string((const char*)&vchRet[0], vchRet.size());
+    return (vchRet.size() == 0) ? std::string() : std::string((const char*)vchRet.data(), vchRet.size());
 }
 
 std::string EncodeBase32(const unsigned char* pch, size_t len)
@@ -415,7 +415,7 @@ std::vector<unsigned char> DecodeBase32(const char* p, bool* pfInvalid)
 std::string DecodeBase32(const std::string& str)
 {
     std::vector<unsigned char> vchRet = DecodeBase32(str.c_str());
-    return (vchRet.size() == 0) ? std::string() : std::string((const char*)&vchRet[0], vchRet.size());
+    return (vchRet.size() == 0) ? std::string() : std::string((const char*) vchRet.data(), vchRet.size());
 }
 
 static bool ParsePrechecks(const std::string& str)