/// <summary>
/// Reads the next number as a <see cref="double"/>.
/// </summary>
/// <param name="reader">A <see cref="TextReader" /> object.</param>
/// <returns>The next number as a <see cref="double"/>; or <c>null</c> if reading fails.</returns>
public static double?ReadNumber(this TextReader reader)
{
int ci;
var negative = false;
double num = 0;
while ((ci = reader.Read()) != -1)
{
var c = (char)ci;
if (ci == '+')
{
c = reader.ReadNonWhitespace();
if (!c.IsASCIIDigit())
{
return(null);
}
num = c - '0';
break;
}
else if (ci == '-')
{
negative = true;
c = reader.ReadNonWhitespace();
if (!c.IsASCIIDigit())
{
return(null);
}
num = c - '0';
break;
}
else if (c.IsASCIIDigit())
{
num = c - '0';
break;
}
}
while ((ci = reader.Read()) != -1 && ((char)ci).IsASCIIDigit())
{
num = num * 10 + ci - '0';
}
if (ci == '.')
{
double @base = 10;
while ((ci = reader.Read()) != -1 && ((char)ci).IsASCIIDigit())
{
num += (ci - '0') / @base;
@base *= 10;
}
}
return(negative ? -num : num);
}
/// <summary>
/// Reads the next integer at most 32-bit large.
/// </summary>
/// <param name="reader">A <see cref="TextReader" /> object.</param>
/// <returns>The next integer; or <c>null</c> if reading fails.</returns>
public static int?ReadInteger(this TextReader reader)
{
int ci;
var negative = false;
int num = 0;
while ((ci = reader.Read()) != -1)
{
var c = (char)ci;
if (ci == '+')
{
c = reader.ReadNonWhitespace();
if (!c.IsASCIIDigit())
{
return(null);
}
num = c - '0';
break;
}
else if (ci == '-')
{
negative = true;
c = reader.ReadNonWhitespace();
if (!c.IsASCIIDigit())
{
return(null);
}
num = c - '0';
break;
}
else if (c.IsASCIIDigit())
{
num = c - '0';
break;
}
}
while ((ci = reader.Read()) != -1 && ((char)ci).IsASCIIDigit())
{
num = num * 10 + ci - '0';
}
return(negative ? -num : num);
}
