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authorTomasz Kramkowski <tk@the-tk.com>2015-04-04 20:42:29 +0200
committerTomasz Kramkowski <tk@the-tk.com>2015-04-04 20:42:29 +0200
commitb99f95ef777000743404902c76c9c8f0b207e5ba (patch)
tree52a9d86ec6855440e0508aa3479d81a9964f5452
parent6aec103b134f3229e3b0329508c9bd5bd423e880 (diff)
downloadc-stuff-b99f95ef777000743404902c76c9c8f0b207e5ba.tar.gz
c-stuff-b99f95ef777000743404902c76c9c8f0b207e5ba.tar.xz
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shufflechars: Shuffle characters around.
-rw-r--r--shufflechars.c59
1 files changed, 59 insertions, 0 deletions
diff --git a/shufflechars.c b/shufflechars.c
new file mode 100644
index 0000000..84a2c55
--- /dev/null
+++ b/shufflechars.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2015 Tomasz Kramkowski <tk@the-tk.com>
+ *
+ * This program is free software. It is licensed under version 3 of the
+ * GNU General Public License.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see [http://www.gnu.org/licenses/].
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <time.h>
+
+static inline unsigned rand_to_max(unsigned max)
+{
+ double random;
+
+ while ((random = rand()) == (double)RAND_MAX);
+
+ return random / (double)RAND_MAX * (double)max;
+}
+
+int main(int argc, char **argv)
+{
+ size_t length;
+ char *text, *dest;
+
+ srand(time(NULL));
+
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s <text>\a\n", argv[0]);
+ exit(EXIT_FAILURE);
+ }
+
+ text = argv[1];
+ length = strlen(text);
+
+ bool relocated[length];
+
+ memset(relocated, 0, length);
+ dest = malloc(length + 1);
+
+ for (size_t i = 0; i < length; i++) {
+ size_t index;
+ while (index = rand_to_max(length), relocated[index])
+ ;
+
+ dest[i] = text[index];
+ relocated[index] = true;
+ }
+
+ dest[length] = '\0';
+
+ printf("%s\n", dest);
+
+ return EXIT_SUCCESS;
+}