2 files changed, 51 insertions, 0 deletions
diff --git a/challenge-097/abigail/README.md b/challenge-097/abigail/README.md
index 6d03a861aa..50f59dc1e2 100644
--- a/challenge-097/abigail/README.md
+++ b/challenge-097/abigail/README.md
@@ -26,6 +26,7 @@ to indicate the left shift.
 ### Solutions
 * [AWK](awk/ch-1.awk)
 * [Bash](bash/ch-1.sh)
+* [C](c/ch-1.c)
 * [Node.js](node/ch-1.js)
 * [Perl](perl/ch-1.pl)
 
diff --git a/challenge-097/abigail/c/ch-1.c b/challenge-097/abigail/c/ch-1.c
new file mode 100644
index 0000000000..8219361e36
--- /dev/null
+++ b/challenge-097/abigail/c/ch-1.c
@@ -0,0 +1,50 @@
+# include <stdlib.h>
+# include <stdio.h>
+# include <string.h>
+# include <unistd.h>
+# include <ctype.h>
+
+/*
+ * See ../README.md
+ */
+
+/*
+ * Run as: cc -o ch-1.o ch-1.c; ./ch-1.o -s SHIFT < input-file
+ */
+
+int main (int argc, char ** argv) {
+    char *  line    = NULL;
+    size_t  len     = 0;
+    size_t  strlen;
+    int     ch;
+    int     shift   = -1;
+    int     NR_OF_LETTERS = 26;
+
+    while ((ch = getopt (argc, argv, "s:")) != -1) {
+        switch (ch) {
+            case 's':
+                shift = atoi (optarg) % NR_OF_LETTERS;
+                break;
+        }
+    }
+    if (shift < 0) {
+        fprintf (stderr, "Requires an -s parameter\n");
+        exit (1);
+    }
+
+    while ((strlen = getline (&line, &len, stdin)) != -1) {
+        char * line_ptr = line;
+        while (* line_ptr) {
+            if (isupper (* line_ptr)) {
+                * line_ptr -= shift;
+                if (* line_ptr < 'A') {
+                    * line_ptr += NR_OF_LETTERS;
+                }
+            }
+            line_ptr ++;
+        }
+        printf ("%s", line);
+    }
+    free (line);
+    return (0);
+}