Add _int.pow

2 files changed, 28 insertions, 0 deletions

diff --git a/src/lib/_int.rs b/src/lib/_int.rs
index ee660f01..ef1b3b66 100644
--- a/src/lib/_int.rs
+++ b/src/lib/_int.rs
@@ -34,6 +34,23 @@ fn to_str(mutable int n, uint radix) -> str
     }
 }
 
+fn pow(int base, uint exponent) -> int {
+
+    if (exponent == 0u) {
+        ret 1;
+    } else if (base == 0) {
+        ret 0;
+    } else {
+        auto accum = base;
+        auto count = exponent;
+        while (count > 1u) {
+            accum *= base;
+            count -= 1u;
+        }
+        ret accum;
+    }
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;
diff --git a/src/test/run-pass/lib-int.rs b/src/test/run-pass/lib-int.rs
index 153c3683..2e85abf6 100644
--- a/src/test/run-pass/lib-int.rs
+++ b/src/test/run-pass/lib-int.rs
@@ -11,6 +11,17 @@ fn test_to_str() {
   check (eq(_int.to_str(100, 10u), "100"));
 }
 
+fn test_pow() {
+  check (_int.pow(0, 0u) == 1);
+  check (_int.pow(0, 1u) == 0);
+  check (_int.pow(0, 2u) == 0);
+  check (_int.pow(-1, 0u) == -1);
+  check (_int.pow(1, 0u) == 1);
+  check (_int.pow(-3, 2u) == 9);
+  check (_int.pow(-3, 3u) == -27);
+  check (_int.pow(4, 9u) == 262144);
+}
+
 fn main() {
   test_to_str();
 }