From 0500d49acb132f57a4bb4e5a8e7b86e9c7d61710 Mon Sep 17 00:00:00 2001
From: cflip <cflip@cflip.net>
Date: Tue, 12 Apr 2022 17:53:04 -0600
Subject: [PATCH] LibC+LibCore: Properly format 12-hour formatted hours

This fixes a small formatting issue where midnight and noon would
display as 00 when they should display as 12.
---
 Userland/Libraries/LibC/time.cpp        | 16 ++++++++++++----
 Userland/Libraries/LibCore/DateTime.cpp | 16 ++++++++++++----
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/Userland/Libraries/LibC/time.cpp b/Userland/Libraries/LibC/time.cpp
index c28351c97a..a2a7b4eee8 100644
--- a/Userland/Libraries/LibC/time.cpp
+++ b/Userland/Libraries/LibC/time.cpp
@@ -250,9 +250,13 @@ size_t strftime(char* destination, size_t max_size, char const* format, const st
             case 'H':
                 builder.appendff("{:02}", tm->tm_hour);
                 break;
-            case 'I':
-                builder.appendff("{:02}", tm->tm_hour % 12);
+            case 'I': {
+                int display_hour = tm->tm_hour % 12;
+                if (display_hour == 0)
+                    display_hour = 12;
+                builder.appendff("{:02}", display_hour);
                 break;
+            }
             case 'j':
                 builder.appendff("{:03}", tm->tm_yday + 1);
                 break;
@@ -268,9 +272,13 @@ size_t strftime(char* destination, size_t max_size, char const* format, const st
             case 'p':
                 builder.append(tm->tm_hour < 12 ? "a.m." : "p.m.");
                 break;
-            case 'r':
-                builder.appendff("{:02}:{:02}:{:02} {}", tm->tm_hour % 12, tm->tm_min, tm->tm_sec, tm->tm_hour < 12 ? "a.m." : "p.m.");
+            case 'r': {
+                int display_hour = tm->tm_hour % 12;
+                if (display_hour == 0)
+                    display_hour = 12;
+                builder.appendff("{:02}:{:02}:{:02} {}", display_hour, tm->tm_min, tm->tm_sec, tm->tm_hour < 12 ? "a.m." : "p.m.");
                 break;
+            }
             case 'R':
                 builder.appendff("{:02}:{:02}", tm->tm_hour, tm->tm_min);
                 break;
diff --git a/Userland/Libraries/LibCore/DateTime.cpp b/Userland/Libraries/LibCore/DateTime.cpp
index 41c1b7f78c..479c433dfa 100644
--- a/Userland/Libraries/LibCore/DateTime.cpp
+++ b/Userland/Libraries/LibCore/DateTime.cpp
@@ -153,9 +153,13 @@ String DateTime::to_string(StringView format) const
             case 'H':
                 builder.appendff("{:02}", tm.tm_hour);
                 break;
-            case 'I':
-                builder.appendff("{:02}", tm.tm_hour % 12);
+            case 'I': {
+                int display_hour = tm.tm_hour % 12;
+                if (display_hour == 0)
+                    display_hour = 12;
+                builder.appendff("{:02}", display_hour);
                 break;
+            }
             case 'j':
                 builder.appendff("{:03}", tm.tm_yday + 1);
                 break;
@@ -171,9 +175,13 @@ String DateTime::to_string(StringView format) const
             case 'p':
                 builder.append(tm.tm_hour < 12 ? "a.m." : "p.m.");
                 break;
-            case 'r':
-                builder.appendff("{:02}:{:02}:{:02} {}", tm.tm_hour % 12, tm.tm_min, tm.tm_sec, tm.tm_hour < 12 ? "a.m." : "p.m.");
+            case 'r': {
+                int display_hour = tm.tm_hour % 12;
+                if (display_hour == 0)
+                    display_hour = 12;
+                builder.appendff("{:02}:{:02}:{:02} {}", display_hour, tm.tm_min, tm.tm_sec, tm.tm_hour < 12 ? "a.m." : "p.m.");
                 break;
+            }
             case 'R':
                 builder.appendff("{:02}:{:02}", tm.tm_hour, tm.tm_min);
                 break;