我用 c++ 构建了一个简单的计算器，它使用字符，因此 (+,-*,/) 将用作数学运算符，但是当用户输入“=”时它不起作用。
#include <iostream>
#include <string>
#include <sstream>
#include <math.h>
using namespace std;
#define PI 3.14159265359
#define NEWLINE '\n'
void printf(string string)
{
cout << string;
}
int main ()
{
char operation;
double a,b,c, value;
double answer = 0;
bool more = true;
cout << "Welcome to My Calculator\n\nInput a value: ";
cin >> answer;
operations:
cin >> operation;
if (operation != '=') {
if (operation == '+') {
cin >> value;
cout << "\n" << answer << " " << operation << " " << value << "\n";
answer += value;
cout << "Equals " << answer << "\n";
cout << answer << " - New Operation? ";
goto operations;
}
if (operation == '-') {
cin >> value;
cout << "\n" << answer << " " << operation << " " << value << "\n";
answer -= value;
cout << "Equals " << answer << "\n";
cout << answer << " - New Operation? ";
goto operations;
}
if (operation == '*') {
cin >> value;
cout << "\n" << answer << " " << operation << " " << value << "\n";
answer *= value;
cout << "Equals " << answer << "\n\n";
cout << answer << " - New Operation? ";
goto operations;
}
if (operation == '/') {
cin >> value;
cout << "\n" << answer << " " << operation << " " << value << "\n";
answer /= value;
cout << "Equals " << answer << "\n\n";
cout << answer << " - New Operation? ";
goto operations;
}
if (operation == '^') {
cin >> value;
cout << "\n" << answer << " " << operation << " " << value << "\n";
answer = pow(answer, value);
cout << "Equals " << answer << "\n\n";
cout << answer << " - New Operation? ";
goto operations;
}
if (operation == '=') {
cout << "\nFinal Answer = " << answer << "\n\nNew operation [yes/no]: ";
string check;
cin >> check;
if (check == "yes") {
cout << "\nInput value: ";
cin >> answer;
cout << "\n";
goto operations;
} else {
cout << "\nGoodbye for now...\n";
return 0;
}
}
} else {
cout << "Unknown Error! Program Closing...";
return 0;
}
return 0;
}
当用户使用除 = 之外的任何操作时，它都能正常工作，但如果我使用和等号，它就不起作用。
示例程序输出：
Welcome to My Calculator
Input a value: 4
+4
4 + 4
Equals 8
8 - New Operation? - 3
8 - 3
Equals 5
5 - New Operation? * 5
5 * 5
Equals 25
25 - New Operation? /2
25 / 2
Equals 12.5
12.5 - New Operation? ^2
12.5 ^ 2
Equals 156.25
156.25 - New Operation? =
Unknown Error! Program Closing...