add printf esc program

Makefile

@@ -1,5 +1,6 @@
 CFLAGS = -Wall -Werror
 TARGETS = pmerge puniq p4split hd
+TARGETS += pyesc printfesc
 
 all: $(TARGETS)
 

printfesc.c

@@ -0,0 +1,28 @@
+#include <stdio.h>
+
+int
+main(int argc, char *argv[])
+{
+    printf("printf ");
+
+    while (! feof(stdin)) {
+        int c = getchar();
+
+        switch (c) {
+            case EOF:
+                break;
+            case '0' ... '9':
+            case 'A' ... 'Z':
+            case 'a' ... 'z':
+                putchar(c);
+                break;
+            default:
+                printf("\\\\%03o", c);
+                break;
+        }
+    }
+
+    putchar('\n');
+
+    return 0;
+}