2 files changed, 19 insertions, 2 deletions
diff --git a/chapter25/src/main/smp/sys/Scan.smp b/chapter25/src/main/smp/sys/Scan.smp
index acf366f7..acf9fbb8 100644
--- a/chapter25/src/main/smp/sys/Scan.smp
+++ b/chapter25/src/main/smp/sys/Scan.smp
@@ -3,6 +3,7 @@
 // Scanner; a simple string parser.
 struct Scan {
     int !x;                     // Cursor
+    bool !bad;                  // True after a malformed token
     u8[~] buf;                  // Immutable byte array, must be set in 2nd constructor
 
     new Scan = { u8[~] b ->
@@ -19,6 +20,7 @@ struct Scan {
     // True if find required character, and skip it; else False.
     val match = { u8 c ->
         skip();
+        if( x >= buf# ) return false;
         if( buf[x] != c ) return false;
         x++;
         return true;
@@ -28,8 +30,12 @@ struct Scan {
     val number = { ->
         skip();
         bool neg = match('-');
+        if( x >= buf# || buf[x] < '0' || '9' < buf[x] ) {
+            bad = true;
+            return 0;
+        }
         i64 n = 0;
-        while( '0' <= buf[x] & buf[x] <= '9' )
+        while( x < buf# && '0' <= buf[x] & buf[x] <= '9' )
             n = n*10 + (buf[x++] - '0');
         return neg ? -n : n;
     };
diff --git a/chapter25/src/main/smp/sys/aryi64.smp b/chapter25/src/main/smp/sys/aryi64.smp
index 8a154f34..c2bc394f 100644
--- a/chapter25/src/main/smp/sys/aryi64.smp
+++ b/chapter25/src/main/smp/sys/aryi64.smp
@@ -36,6 +36,14 @@ struct aryi64 {
         str.undo(2).add(']');
     };
 
+    // Comma-separated form used by command-line examples.
+    val csv = { ->
+        var str = new aryu8(new u8[1]);
+        for( int i=0; i<len; i++ )
+            str.num(buf[i]).add(',').add(' ');
+        str.undo(2).add('\n');
+    };
+
     val swap = { int i, int j ->
         i64 tmp = buf[i];
         buf[i] = buf[j];
@@ -62,9 +70,12 @@ val parseAryI64 = { u8[~] str ->
     // Parse number commas "123, " until something else
     while( s.x < s.buf# ) {
         nums.add(s.number());
+        if( s.bad ) return null;
         if( !s.match(',') )
             break;
     };
     // Close the list
-    return s.match(']') ? nums : null;
+    if( !s.match(']') ) return null;
+    s.skip();
+    return s.x == s.buf# ? nums : null;
 };