formatting.h: Clarify meaning of cursor in FormatOneChar

felipecrv · Apr 5, 2024 · e9b04fe · e9b04fe
1 parent 83359d6
commit e9b04fe
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/cpp/src/arrow/util/formatting.h b/cpp/src/arrow/util/formatting.h
@@ -126,8 +126,10 @@ namespace detail {
 ARROW_EXPORT extern const char digit_pairs[];
 
 // Based on fmtlib's format_int class:
-// Write digits from right to left into a stack allocated buffer
-inline void FormatOneChar(char c, char** cursor) { *--*cursor = c; }
+// Write digits from right to left into a stack allocated buffer.
+// \pre *cursor points to the byte after the one that will be written.
+// \post *cursor points to the byte that was written.
+inline void FormatOneChar(char c, char** cursor) { *(--(*cursor)) = c; }
 
 template <typename Int>
 void FormatOneDigit(Int value, char** cursor) {