added exit codes

examples/tri_selection/tri.c

@@ -35,4 +35,12 @@ int main() {
         printf("%f ", tab[i]);
     }
     printf("\n");
+
+    for (int i = 0; i < SIZE - 1; ++i) {
+        if (tab[i] > tab[i + 1]) {
+            return EXIT_FAILURE;
+        }
+    }
+
+    return EXIT_SUCCESS;
 }