以下程序输出结果为______。 include<iostream> using namespace std; class TestClass 1 { public: TestClass1(){} TestClass1(int i) {x1=i;} void dispa() {cout<<'x1='<<x1<<',';} private: int x1; }: class TestClass2:public TestClass1 { public: TestClass2(){} TestClass2(int i):TestClass1(i+10) { x2=i: } void dispb() { dispa(); cout<<'x2='<<x2<<end1; } private: int x2: }: int main() { TestClass2 b(2): b.dispb(); return 0; }