1 files changed, 24 insertions, 34 deletions
diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 0329a26db8..c587e9c254 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -64,6 +64,8 @@
 #include <string.h>
 #include <stdlib.h>
 
+#include <algorithm>
+
 #define IS_RAW_DATA(d) ((d)->flags() & QArrayData::RawDataType)
 
 QT_BEGIN_NAMESPACE
@@ -2743,56 +2745,44 @@ static constexpr inline bool isUpperCaseAscii(char c)
     return c >= 'A' && c <= 'Z';
 }
 
+/*
+    Returns true if \a c is an lowercase ASCII letter.
+ */
+static constexpr inline bool isLowerCaseAscii(char c)
+{
+    return c >= 'a' && c <= 'z';
+}
+
 /*!
-    Returns \c true if this byte array contains only ASCII uppercase letters,
-    otherwise returns \c false.
+    Returns \c true if this byte array is uppercase, that is, if
+    it's identical to its toUpper() folding.
+
+    Note that this does \e not mean that the byte array only contains
+    uppercase letters; only that it contains no ASCII lowercase letters.
+
     \since 5.12
 
     \sa isLower(), toUpper()
 */
 bool QByteArray::isUpper() const
 {
-    if (isEmpty())
-        return false;
-
-    const char *d = data();
-
-    for (qsizetype i = 0, max = size(); i < max; ++i) {
-        if (!isUpperCaseAscii(d[i]))
-            return false;
-    }
-
-    return true;
-}
-
-/*
-    Returns true if \a c is an lowercase ASCII letter.
- */
-static constexpr inline bool isLowerCaseAscii(char c)
-{
-    return c >= 'a' && c <= 'z';
+    return std::none_of(begin(), end(), isLowerCaseAscii);
 }
 
 /*!
-    Returns \c true if this byte array contains only lowercase ASCII letters,
-    otherwise returns \c false.
+    Returns \c true if this byte array is lowercase, that is, if
+    it's identical to its toLower() folding.
+
+    Note that this does \e not mean that the byte array only contains
+    lowercase letters; only that it contains no ASCII uppercase letters.
+
     \since 5.12
 
     \sa isUpper(), toLower()
  */
 bool QByteArray::isLower() const
 {
-    if (isEmpty())
-        return false;
-
-    const char *d = data();
-
-    for (qsizetype i = 0, max = size(); i < max; ++i) {
-        if (!isLowerCaseAscii(d[i]))
-            return false;
-    }
-
-    return true;
+    return std::none_of(begin(), end(), isUpperCaseAscii);
 }
 
 /*!