Math in C++

How can I get the program below to reject all characters except numbers and these symbols (-, =, +, *, /, %)

You need to write your own input function using get
something like this:

Code:

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do {
        a = cin.get()
        if ( a == desiredchar )
                input += a
} while ( inputting )

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A switch and case statement may be easier to use.

Code:

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bool ValidChar(char C)
{
  if((C >= '0') && (C <= '9')) return true;
  if(C == '-') return true;
  if(C == '=') return true;
  if(C == '+') return true;
  if(C == '*') return true;
  if(C == '/') return true;
  if(C == '%') return true;
  return false;
}

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Or even

Code:

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bool ValidChar(char C)
{
  return strchr( "0123456789-+*/%=", C ) != NULL;
}

---

:)

Where do I put the bool statement? (I'm a newbie.)