first homework

lesson1/assignment/yours.sol

@@ -1 +1,43 @@
-/*作业请提交在这个目录下*/
+ pragma solidity ^0.4.14;
+
+contract PayRoll {
+    uint salary = 1 ether;
+    address frank = 0xca35b7d915458ef540ade6068dfe2f44e8fa733c;
+    uint constant duration = 10 seconds;
+    uint lastpayday = now;
+
+    function addFund() payable returns (uint) {
+        return this.balance;
+    }
+
+    function calculateRunway() returns (uint) {
+        return this.balance / salary;
+    }
+
+    function hasEnoughfund() returns (bool) {
+        return calculateRunway() > 0;
+    }
+
+    function getPaid() {
+        if(msg.sender != frank) {
+            revert();
+        }
+        uint nextPayday = lastpayday + duration;
+        if (nextPayday >= now) {
+            revert();
+        }
+        lastpayday = nextPayday;
+        frank.transfer(salary);
+    }
+
+    function changeAddress() {
+        frank = msg.sender;
+    }
+
+    function changeSalary() {
+        if (msg.value <= 0) {
+            revert();
+        }
+        salary = msg.value;    
+    }
+}