字符到运算符 C++
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Char to Operator C++
提问by wzsun
Hey I wanted to know how you could turn a character '+' into an operator. For example if I had
嘿，我想知道如何将字符“+”转换为运算符。例如，如果我有
char op = '+'
cout << 6 op 1;
Thanks.
谢谢。
回答by john
SImple way is to use a switch statement
简单的方法是使用 switch 语句
switch (op)
{
case '+':
res = x + y;
break;
case '-':
res = x - y;
break;
case '*':
res = x * y;
break;
}
回答by Dan
I don't think there's a way as you've written it there but you could do something hacky like
我不认为有你在那里写的方法，但你可以做一些像
int do_op(char op, int a, int b)
{
switch(op)
{
case '+':
return a+b;
break;
case '-':
return a-b;
break;
case '*':
return a*b;
break;
case '/':
return a/b;
break;
default:
throw std::runtime_error("unknown op")
}
}
回答by argothiel
You may use an old-way #define:
您可以使用旧方式#define：
#define op +
std::cout << 6 op 1;
However it has limited use.
然而，它的用途有限。
If you want to do this in pure C++, you will have to use switch syntax either explicitely or in an external library (like tetzfamily.com/temp/EvalDoc.htm or codeproject.com/Articles/7939/C-based-Expression-Evaluation-Library)).
如果您想在纯 C++ 中执行此操作，则必须明确地或在外部库中使用 switch 语法（如 tetzfamily.com/temp/EvalDoc.htm 或 codeproject.com/Articles/7939/C-based-Expression-评估库））。
Another way is to use an external program, like bc:
另一种方法是使用外部程序，例如 bc：
char op = '+';
std::string s;
s += "6";
s += op;
s += "4";
system(("echo " + s + "|bc").c_str());
If you want to use the result later, check the popenfunction or the C++ equivalent.
回答by user2722684
public class ArithmeticOps {
static int testcase11 = 11;
static int testcase12 = 3;
static char testcase13 = '/';
public static void main(String args[]){
ArithmeticOps testInstance = new ArithmeticOps();
int result = testInstance.compute(testcase11,testcase12,testcase13);
System.out.println(result);
}
public int compute(int a, int b,char operator){
int i=0;
switch(operator)
{
case '+' :
i= a+b;
break;
case '-' :
i= a-b;
break;
case '*' :
i= a*b;
break;
case '/' :
i= a/b;
break;
case '%' :
i= a%b;
break;
case '^' :
i= a^b;
break;
default:
i=0;
}
return i;
}
}
}
