Index: aoc2024.c
==================================================================
--- aoc2024.c
+++ aoc2024.c
@@ -1,10 +1,39 @@
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "aocutils.h"
+
+void aoc202403(char *data, [[maybe_unused]] size_t len) {
+    int sumproducts = 0, term[2];
+    char *rest = data;
+    for (;;) {
+        char *mul = strstr(rest, "mul(");
+        if (mul) {
+            rest = mul + 4;
+            if (isdigit((unsigned char)rest[0])) {
+                char *err;
+                term[0] = (int)strtol(rest, &err, 10);
+                if (*err == ',') {
+                    if (isdigit((unsigned char)err[1])) {
+                        rest = err + 1;
+                        term[1] = (int)strtol(rest, &err, 10);
+                        if (*err == ')') {
+                            sumproducts += term[0] * term[1];
+                            rest = err + 1;
+                        }
+                    }
+                }
+            }
+        } else {
+            break;
+        }
+    }
+    printf("The sum of the products is {%d}.\n", sumproducts);
+}
 
 static int safereport(int *v, int nv) {
     int dir = 1;               // ascending
     if (v[0] > v[1]) dir = -1; // descending
     for (int k = 1; k < nv; k++) {

Index: aocdailies.c
==================================================================
--- aocdailies.c
+++ aocdailies.c
@@ -34,8 +34,9 @@
         case 201525: p = aoc201525; break;
         #endif
 
         case 202401: p = aoc202401; break;
         case 202402: p = aoc202402; break;
+        case 202403: p = aoc202403; break;
     }
     return p;
 }

Index: aocdailies.h
==================================================================
--- aocdailies.h
+++ aocdailies.h
@@ -34,7 +34,8 @@
 aocfunc aoc201525;
 #endif
 
 aocfunc aoc202401;
 aocfunc aoc202402;
+aocfunc aoc202403;
 
 #endif