Merge remote-tracking branch 'upstream/master'

src/calc.cpp

@@ -9,6 +9,7 @@ int minus(   int a, int b) { return a - b; }
 int multiply(int a, int b) { return a * b; }
 int divide(  int a, int b) { return a / b; }
 int pow(   int a, int b) { return std::pow(a, b); }
+int modulo(  int a, int b) { return a % b; }
 
 int pop_stack(auto &stack) {
   const auto ret{stack.top()};
@@ -32,6 +33,7 @@ int evaluate(const std::string &s) {
     case '*': change_stack_state(multiply, stack); break;
     case '/': change_stack_state(divide,   stack); break;
     case '^': change_stack_state(pow,    stack); break;
+    case '%': change_stack_state(modulo,   stack); break;
     case '0'...'9': stack.push(c - '0'); break;
     }
   }

test/test.cpp

@@ -12,3 +12,9 @@ TEST_CASE( "pow function works", "[calc]") {
   REQUIRE( evaluate("43^") == 64 );
   REQUIRE_FALSE( evaluate("11^") == 2);
 }
+
+TEST_CASE( "Test modulo function", "[calc]") {
+  REQUIRE( evaluate("11%") == 0 );
+  REQUIRE( evaluate("32%") == 1 );
+  REQUIRE( evaluate("51%") == 0 );
+}