Make should make printy. Also docs.

Makefile

@@ -16,6 +16,7 @@ TARGETS += hex
 TARGETS += entropy
 TARGETS += freq
 TARGETS += histogram
+TARGETS += printy
 
 SCRIPTS += octets
 

README.md

@@ -232,6 +232,19 @@ Displays the Shannon entropy of the input.
     0.865857
 
 
+## printy: show density of printable octets
+
+Displays the number of printable octets
+divided by the total number of octets.
+
+    $ echo -n abcd | ./printy
+    1.000000
+    $ echo abcd | ./printy   # Newline is not printable
+    0.800000
+    $ echo 00 41 | ./unhex | ./printy
+    0.500000
+
+
 ## pyesc: python escape input
 
 Escapes input octets for pasting into a python "print" statement.

printy.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <ctype.h>
+
+int main(int argc, char *argv[]) {
+    int c;
+    unsigned int count = 0;
+    unsigned int printy = 0;
+
+    for (;;) {
+        c = getchar();
+        if (EOF == c) {
+            break;
+        }
+        if (isprint(c)) {
+            printy += 1;
+        }
+        count += 1;
+    }
+
+    printf("%f\n", printy/(float)count);
+
+    return 0;
+}