以这个写一个任意数字关于加减乘除的调用构造函数的c++代码

```c #include <stdio.h> typedef struct { int num; char op; } Expression; Expression create_expression(int num, char op) { Expression e; e.num = num; e.op = op; return e; } int evaluate_expression(Expression e) { switch (e.op) { case '+': return e.num + evaluate_expression(create_expression(0, '+')); case '-': return e.num - evaluate_expression(create_expression(0, '+')); case '*': return e.num * evaluate_expression(create_expression(0, '+')); case '/': return e.num / evaluate_expression(create_expression(1, '+')); default: return e.num; } } int main() { int num = 5; char op = '+'; Expression e = create_expression(num, op); int result = evaluate_expression(e); printf("表达式 %d %c %d = %d ", num, op, num, result); return 0; } ```