Add examples: sum, prod, avg, median

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 63 insertions, 0 deletions

diff --git a/examples/04-median.c b/examples/04-median.c
new file mode 100644
index 0000000..7acff70
--- /dev/null
+++ b/examples/04-median.c
@@ -0,0 +1,63 @@
+/* Calculates the median of $@ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <zahl.h>
+
+int
+main(int argc, char *argv[])
+{
+	struct zahl *values;
+	z_t med, medmod;
+	jmp_buf env;
+	char *buf, *argv0;
+	int i, j;
+
+	argv0 = *argv++, argc--;
+
+	if (!argc) {
+		fprintf(stderr,
+		        "%s: cannot calculate median of the empty bag\n",
+		        argv0);
+		return 1;
+	}
+
+	values = calloc(argc, sizeof(*values));
+	if (!values)
+		return perror(argv0), 1;
+
+	if (setjmp(env))
+		return zperror(argv0), 1;
+
+	zsetup(env);
+	zinit(med);
+	zinit(medmod);
+
+	/* Since `values` where allocated with
+	 * `calloc` it is already cleared and
+	 * `zinit` is not necessary. */
+
+	for (i = 0; i < argc; i++)
+		zsets(&values[i], argv[i]);
+
+	qsort(values, argc, sizeof(*values),
+	      (int (*)(const void *, const void *))zcmp);
+	i = argc / 2;
+	j = i - !(argc & 1);
+	zadd(med, &values[i], &values[j]);
+	zsetu(medmod, 2);
+	zdivmod(med, medmod, med, medmod);
+
+	printf("%s%s\n", buf = zstr(med, NULL, 0),
+	               (const char *[]){"", ".5"}[zodd(medmod)]);
+	free(buf);
+
+	zfree(medmod);
+	zfree(med);
+	for (i = 0; i < argc; i++)
+		zfree(&values[i]);
+	free(values);
+	zunsetup();
+	return 0;
+}