chore: initial commit

day_1.c

@@ -0,0 +1,51 @@
+//
+// Created by Lennart on 02/12/2023.
+//
+
+#include <stdio.h>
+#include "main.h"
+
+int read_line(FILE *f);
+
+int day_1() {
+    FILE *f = fopen("day_1.txt", "r");
+    if(f == NULL) {
+        printf("Error! Missing input file!");
+        return -1;
+    }
+
+    int sum = 0;
+    while(!feof(f)) {
+        sum += read_line(f);
+    }
+
+    fclose(f);
+    printf("Result: %i\n", sum);
+    return 0;
+}
+
+// Read all digits form the next line in a file
+int read_line(FILE *f) {
+    int first = -1, last = 10; // Use first=-1 to detect unset value and last=10 to return 0 (-10 + 10) when no values are set
+    char buffer[16];
+    int digit;
+    do {
+        fgets(&buffer[0], 16, f);
+        for(int i = 0; i < 16; i++) {
+            if(buffer[i] == '\n') {
+                goto result;
+            } else if(buffer[i] == 0) {
+                break; // End of buffer
+            }
+            if(sscanf(&buffer[i], "%1d", &digit) == 1) { // NOLINT(*-err34-c)
+                if(first == -1) {
+                    first = digit;
+                }
+                last = digit;
+            }
+        }
+    } while(!feof(f));
+
+    result:
+    return first * 10 + last;
+}