A-M baby

Task/Filter/C/filter.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int even_sel(int x) { return !(x & 1); }
+int tri_sel(int x) { return x % 3; }
+
+/* using a predicate function sel() to select elements */
+int* grep(int *in, int len, int *outlen, int (*sel)(int), int inplace)
+{
+	int i, j, *out;
+
+	if (inplace)	out = in;
+	else		out = malloc(sizeof(int) * len);
+
+	for (i = j = 0; i < len; i++)
+		if (sel(in[i]))
+			out[j++] = in[i];
+
+	if (!inplace && j < len)
+		out = realloc(out, sizeof(int) * j);
+
+	*outlen = j;
+	return out;
+}
+
+int main()
+{
+	int in[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
+	int i, len;
+
+	int *even = grep(in, 10, &len, even_sel, 0);
+	printf("Filtered even:");
+	for (i = 0; i < len; i++) printf(" %d", even[i]);
+	printf("\n");
+
+	grep(in, 8, &len, tri_sel, 1);
+	printf("In-place filtered not multiple of 3:");
+	for (i = 0; i < len; i++) printf(" %d", in[i]);
+
+	printf("\n");
+
+	return 0;
+}