1 //---------------+-*/%算法----------------------------------------------------------
2 #include <iostream>
3 using namespace std;
4 // 函数原型声明
5 int Add(int e1, int e2);
6 int Sub(const int*pe1, const int*pe2);
7 int Mul(const int&re1, const int&re2);
8 int Div(int e1, int e2)throw(int); // 分母不能为0，否则抛出除0错
9 int Mod(int e1,int e2)throw(int,long); //分子 分母不能为0，否则抛出无意义错或除0错
10
11 void main() {
12 int e1, e2, result;
13 char optr;
14
15 while (true) {
16 cout <<
17 "Please type in an expression which likes a @b,type 'q' to quit" << endl;
18 cin >> optr;
19 if (optr == 'q' || optr == 'Q')
20 break; // 结束循环
21 cin.putback(optr); // 将读入的字符退回到流中，让它可以被重新读入
22 cin >> e1;
23 cin >> optr;
24 cin >> e2;
25
26 switch(optr) {
27 case '+':
28 result = Add(e1, e2);
29 break;
30 case '-':
31 result = Sub(&e1, &e2);
32 break;
33 case '*':
34 result = Mul(e1, e2);
35 break;
36 case '/':
37 result = Div(e1, e2);
38 break;
39 case '%':
40 result = Mod(e1, e2);
41 break;
42 }
43 }
44 system("pause");
45 }
46
47 int Add(int e1, int e2) {
48 int result = e1 + e2;
49 cout << '=' << result << endl;
50 return result;
51 }
52
53 int Sub(const int *pe1, const int *pe2) {
54 int result = *pe1 - *pe2; // 指针指向的内存地址里面存的数值相减
55 cout << '=' << result << endl;
56 return result;
57 }
58
59 int Mul(const int &re1, const int &re2) {
60 int result = re1 * re2;
61 cout << '=' << result << endl;
62 return result;
63 }
64
65 int Div(int e1, int e2)throw(int) {
66 try {
67 if (e2 == 0)
68 throw 0;
69 int result = e1 / e2;
70 cout << '=' << result << endl;
71 return result;
72 }
73 catch(int) {
74 cout << "Denominator cannot be zero" << endl;
75 }
76
77 }
78
79 int Mod(int e1,int e2)throw(int,long)
80 {
81 try
82 {
83 if(e1==0)
84 throw int(0);
85 if(e2==0)
86 throw long(0);
87
88 int result=e1%e2;
89 cout << '=' << result << endl;
90 return result;
91 }
92 catch(int)
93 {
94 cout<<"It doesn't make sense when numerator is zero"<<endl;
95 }
96 catch(long)
97 {
98 cout<<"Denominator cannot be zero"<<endl;
99 }
100 }
