Index: aoc2024.c
==================================================================
--- aoc2024.c
+++ aoc2024.c
@@ -5,10 +5,20 @@
 #include <stdlib.h>
 #include <string.h>
 
 #include "aocdailies.h"
 #include "aocutils.h"
+
+void aoc202404(char *data, size_t len) {
+    (void)len; // unused argument
+    // assume data is well-formatted and has the same number of rows and columns
+    unsigned cols = strchr(data, '\n') - data, rows = cols;
+    printf("data has %u cols, first three rows start with %c%c, %c%c, and %c%c.\n",
+          rows, data[0], data[1],
+          data[1*(cols+1)], data[1*(cols+1)+1],
+          data[2*(cols+1)], data[2*(cols+1)+1]);
+}
 
 void aoc202403(char *data, size_t len) {
     (void)len; // unused argument
     unsigned sumproducts = 0, sumproducts2 = 0, term[2];
     char *rest = data;

Index: aocdailies.c
==================================================================
--- aocdailies.c
+++ aocdailies.c
@@ -4,10 +4,11 @@
 aocfunc *aocselect(unsigned y, unsigned d) {
     aocfunc *p;
     switch (y * 100 + d) {
         default: p = NULL; break;
 
+        case 202404: p = aoc202404; break;
         case 202403: p = aoc202403; break;
         case 202402: p = aoc202402; break;
         case 202401: p = aoc202401; break;
 
         #if 0

Index: aocdailies.h
==================================================================
--- aocdailies.h
+++ aocdailies.h
@@ -4,10 +4,11 @@
 #include <stddef.h>
 
 typedef void aocfunc(char *, size_t);
 aocfunc *aocselect(unsigned, unsigned);
 
+aocfunc aoc202404;
 aocfunc aoc202403;
 aocfunc aoc202402;
 aocfunc aoc202401;
 
 #if 0