Int32 Parsing differences

Convert.cs

public static int Convert.ToInt32(string value)
{
    if (value == null) return 0;
    return Int32.Parse(value, CultureInfo.CurrentCulture);
}

Int32.cs

public static int Int32.Parse(string s)
{
    if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
    return Number.ParseInt32(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo);
}

public static bool Int32.TryParse(string s, out int result)
{
    if (s == null)
    {
        result = 0;
        return false;
    }
    return Number.TryParseInt32(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo, out result);
}

Numbers.cs

internal static int ParseInt32(ReadOnlySpan<char> value, NumberStyles styles, NumberFormatInfo info)
{
    if ((styles & ~NumberStyles.Integer) == 0)
    {
        // Optimized path for the common case of anything that's allowed for integer style.
        bool overflow = false;
        if (!TryParseInt32IntegerStyle(value, styles, info, out int intResult, ref overflow))
        {
            ThrowOverflowOrFormatException(overflow, nameof(SR.Overflow_Int32));
        }
        return intResult;
    }

    // SOME CODE REMOVED FOR READABILITY   
    
    NumberBuffer number = default;
    int result = 0;
    
    StringToNumber(value, styles, ref number, info, false);
    if (!NumberToInt32(ref number, ref result))
    {
        ThrowOverflowOrFormatException(overflow: true, nameof(SR.Overflow_Int32));
    }
    return result;

}

internal static bool TryParseInt32(ReadOnlySpan<char> value, NumberStyles styles, NumberFormatInfo info, out int result)
{
    if ((styles & ~NumberStyles.Integer) == 0)
    {
        // Optimized path for the common case of anything that's allowed for integer style.
        bool overflow = false;
        return TryParseInt32IntegerStyle(value, styles, info, out result, ref overflow);
    }

    // SOME CODE REMOVED FOR READABILITY   
    
    NumberBuffer number = default;
    result = 0;
    
    return
        TryStringToNumber(value, styles, ref number, info, false) &&
        NumberToInt32(ref number, ref result);
}


private static unsafe void StringToNumber(ReadOnlySpan<char> value, NumberStyles styles, ref NumberBuffer number, NumberFormatInfo info, bool parseDecimal)
{
   // SOME CODE REMOVED FOR READABILITY 
    fixed (char* stringPointer = &MemoryMarshal.GetReference(value))
    {
        char* p = stringPointer;
        if (!ParseNumber(ref p, p + value.Length, styles, ref number, info, parseDecimal)
            || (p - stringPointer < value.Length && !TrailingZeros(value, (int)(p - stringPointer))))
        {
            ThrowOverflowOrFormatException(overflow: false, null);
        }
    }
}

internal static unsafe bool TryStringToNumber(ReadOnlySpan<char> value, NumberStyles styles, ref NumberBuffer number, NumberFormatInfo info, bool parseDecimal)
{
    // SOME CODE REMOVED FOR READABILITY 
    fixed (char* stringPointer = &MemoryMarshal.GetReference(value))
    {
        char* p = stringPointer;
        if (!ParseNumber(ref p, p + value.Length, styles, ref number, info, parseDecimal)
            || (p - stringPointer < value.Length && !TrailingZeros(value, (int)(p - stringPointer))))
        {
            return false;
        }
    }

    return true;
}

private static bool TryParseInt32IntegerStyle(ReadOnlySpan<char> value, NumberStyles styles, NumberFormatInfo info, out int result, ref bool failureIsOverflow) => // SOME CODE REMOVED FOR READABILITY 
private static unsafe bool ParseNumber(ref char* str, char* strEnd, NumberStyles styles, ref NumberBuffer number, NumberFormatInfo info, bool parseDecimal) => // SOME CODE REMOVED FOR READABILITY         
private static bool TrailingZeros(ReadOnlySpan<char> value, int index) =>  // SOME CODE REMOVED FOR READABILITY        
private static unsafe char* MatchChars(char* p, char* pEnd, string value) => // SOME CODE REMOVED FOR READABILITY        
private static bool IsWhite(int ch) => // SOME CODE REMOVED FOR READABILITY 
private static bool IsDigit(int ch) => // SOME CODE REMOVED FOR READABILITY 
private static void ThrowOverflowOrFormatException(bool overflow, string overflowResourceKey) => // SOME CODE REMOVED FOR READABILITY;                 
private static unsafe bool ParseNumber(ref char* str, char* strEnd, NumberStyles styles, ref NumberBuffer number, NumberFormatInfo info, bool parseDecimal) => // SOME CODE REMOVED FOR READABILITY