Real argc/argv args

Beef up BubbleSort error handling

1 files changed, 14 insertions, 8 deletions

diff --git a/chapter25/docs/examples/BubbleSort.smp b/chapter25/docs/examples/BubbleSort.smp
index 864e26da..1a4359ae 100644
--- a/chapter25/docs/examples/BubbleSort.smp
+++ b/chapter25/docs/examples/BubbleSort.smp
@@ -17,17 +17,23 @@ val sort = { sys.aryi64 nums ->
     }
 };
 
-// Read from stdin a line of the form "[ 4, 3, 2, 1]" and print it sorted.
-val main = { ->
-    // Parse array of numbers from stdin
-    var nums = sys.aryi64.parseAryI64( sys.io.stdin() );
-    if( !nums )
-        return sys.io.p("stdin must look like [4, 3, 2, 1]");
+// Read one process argument of the form "[ 4, 3, 2, 1]" and print it sorted.
+// args[0] is the executable name, as with native C argc/argv.
+val main = { u8[~][] args ->
+    val usage = { ->
+        sys.io.p("Usage: please provide a list of at least two integers to sort in the format \"[1, 2, 3, 4, 5]\"\n");
+        return 0;
+    };
+    if( args# != 2 ) return usage();
+
+    var nums = sys.aryi64.parseAryI64(args[1]);
+    if( !nums ) return usage();
+    if( nums.len < 2 ) return usage();
 
     // Bubble sort array of integers
     sort(nums);
 
-    // Print a list of numbers to stdout
-    nums.str().write(1);
+    // Print the comma-separated result without the input brackets.
+    nums.csv().write(1);
     return 0;
 };