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Separated expression string processing to its own method and created basic REPL

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This commit is contained in:
Dmitriy Shishkov 2021-08-08 19:03:15 +03:00
parent 4a27d77713
commit 8234e92ce1
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GPG Key ID: 14358F96FCDD8060
1 changed files with 85 additions and 45 deletions
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130
Program.cs
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@ -8,60 +8,76 @@ namespace calculator
static void Main(string[] args)
{
if (args.Length == 0)
Console.WriteLine("REPL is not ready yet. Please, provide mathematic expression as an argument");
else
try
{
string input = readREPL();
while (input != null)
{
string[] expr = args[0].Split();
Stack<double> st = new Stack<double>();
writeREPL(evaluate(input));
input = readREPL();
}
}
else
{
writeREPL(evaluate(args[0]));
}
}
for (int i = 0; i < expr.Length; i++)
static private double evaluate(string s)
{
try
{
string[] expr = s.Split();
Stack<double> st = new Stack<double>();
for (int i = 0; i < expr.Length; i++)
{
object val = convertOne(expr[i]);
if (val is double number)
st.Push(number);
else if (val is char oper)
{
object val = convertOne(expr[i]);
if (val is double number)
st.Push(number);
else if (val is char oper)
try
{
try
double b = st.Pop();
double a = st.Pop();
switch (oper)
{
double b = st.Pop();
double a = st.Pop();
switch (oper)
{
case '+':
st.Push(a + b);
break;
case '-':
st.Push(a - b);
break;
case '*':
st.Push(a * b);
break;
case '/':
st.Push(a / b);
break;
case '^':
st.Push(Math.Pow(a, b));
break;
default:
throw new Exception("Got unknown operator");
}
}
catch (InvalidOperationException)
{
throw new Exception(oper + " operation requires two operands");
case '+':
st.Push(a + b);
break;
case '-':
st.Push(a - b);
break;
case '*':
st.Push(a * b);
break;
case '/':
st.Push(a / b);
break;
case '^':
st.Push(Math.Pow(a, b));
break;
default:
throw new Exception("Got unknown operator");
}
}
else throw new Exception("Stack corrupted");
catch (InvalidOperationException)
{
throw new Exception(oper + " operation requires two operands");
}
}
else throw new Exception("Stack corrupted");
}
Console.WriteLine(st.Pop());
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
return st.Pop();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
Environment.Exit(1);
return -1;
}
}
static private object convertOne(string s)
@ -71,5 +87,29 @@ namespace calculator
else if (s.Length == 1) return s[0];
else throw new Exception("Got multiple characters operator");
}
static private string readREPL()
{
Console.Write(">> ");
string input = Console.ReadLine();
switch (input)
{
case "exit":
case "exit()":
case "quit":
case "quit()":
case "q":
case "":
return null;
default:
return input;
}
}
static private void writeREPL<T>(T o)
{
Console.WriteLine(o);
}
}
}