# UInt64::Parse Method (String, NumberStyles)

**.NET Framework 4.6 and 4.5**

Converts the string representation of a number in a specified style to its 64-bit unsigned integer equivalent.

This API is not CLS-compliant. The CLS-compliant alternative is Parse.

**Namespace:**System

**Assembly:**mscorlib (in mscorlib.dll)

[CLSCompliantAttribute(false)] public: static unsigned long long Parse( String^ s, NumberStyles style )

#### Parameters

- s
- Type: System::String
A string that represents the number to convert. The string is interpreted by using the style specified by the style parameter.

- style
- Type: System.Globalization::NumberStyles
A bitwise combination of the enumeration values that specifies the permitted format of s. A typical value to specify is NumberStyles::Integer.

Exception | Condition |
---|---|

ArgumentNullException | The s parameter is nullptr. |

ArgumentException | style is not a NumberStyles value. -or- style is not a combination of AllowHexSpecifier and HexNumber values. |

FormatException | The s parameter is not in a format compliant with style. |

OverflowException | The s parameter represents a number less than UInt64::MinValue or greater than UInt64::MaxValue. -or- s includes non-zero, fractional digits. |

The style parameter defines the style elements (such as white space, the positive or negative sign symbol, the group separator symbol, or the decimal point symbol) that are allowed in the s parameter for the parse operation to succeed. style must be a combination of bit flags from the NumberStyles enumeration. The style parameter makes this method overload useful when s contains the string representation of a hexadecimal value, when the number system (decimal or hexadecimal) represented by s is known only at run time, or when you want to disallow white space or a sign symbol in s.

Depending on the value of style, the s parameter may include the following elements:

[ws][$][sign][digits,]digits[.fractional_digits][E[sign]exponential_digits][ws]

Elements in square brackets ([ and ]) are optional. If style includes NumberStyles::AllowHexSpecifier, the s parameter may contain the following elements:

[ws]hexdigits[ws]

The following table describes each element.

Element | Description |
---|---|

ws | Optional white space. White space can appear at the start of s if style includes the NumberStyles::AllowLeadingWhite flag, and it can appear at the end of s if style includes the NumberStyles::AllowTrailingWhite flag. |

$ | A culture-specific currency symbol. Its position in the string is defined by the NumberFormatInfo::CurrencyNegativePattern and NumberFormatInfo::CurrencyPositivePattern properties of the current culture. The current culture's currency symbol can appear in s if style includes the NumberStyles::AllowCurrencySymbol flag. |

sign | An optional sign. The sign can appear at the start of s if style includes the NumberStyles::AllowLeadingSign flag, and it can appear at the end of s if style includes the NumberStyles::AllowTrailingSign flag. Parentheses can be used in s to indicate a negative value if style includes the NumberStyles::AllowParentheses flag. However, the negative sign symbol can be used only with zero; otherwise, the method throws an OverflowException. |

digits fractional_digits exponential_digits | A sequence of digits from 0 through 9. For fractional_digits, only the digit 0 is valid. |

, | A culture-specific group separator symbol. The current culture's group separator can appear in s if style includes the NumberStyles::AllowThousands flag. |

. | A culture-specific decimal point symbol. The current culture's decimal point symbol can appear in s if style includes the NumberStyles::AllowDecimalPoint flag. Only the digit 0 can appear as a fractional digit for the parse operation to succeed; if fractional_digits includes any other digit, a FormatException is thrown. |

E | The "e" or "E" character, which indicates that the value is represented in exponential (scientific) notation. The s parameter can represent a number in exponential notation if style includes the NumberStyles::AllowExponent flag. |

hexdigits | A sequence of hexadecimal digits from 0 through f, or 0 through F. |

A string with digits only (which corresponds to the NumberStyles::None style) always parses successfully. Most of the remaining NumberStyles members control elements that may be present, but are not required to be present, in the input string. The following table indicates how individual NumberStyles members affect the elements that may be present in s.

NumberStyles value | Elements permitted in s in addition to digits |
---|---|

The digits element only. | |

The decimal point (.) and fractional-digits elements. | |

The "e" or "E" character, which indicates exponential notation, along with exponential_digits. | |

The ws element at the start of s. | |

The ws element at the end of s. | |

The sign element at the start of s. | |

The sign element at the end of s. | |

The sign element in the form of parentheses enclosing the numeric value. | |

The group separator (,) element. | |

The currency ($) element. | |

All elements. However, s cannot represent a hexadecimal number or a number in exponential notation. | |

The ws element at the start or end of s, sign at the start of s, and the decimal point (.) symbol. The s parameter can also use exponential notation. | |

The ws, sign, group separator (,), and decimal point (.) elements. | |

All elements. However, s cannot represent a hexadecimal number. |

Unlike the other NumberStyles values, which allow for, but do not require, the presence of particular style elements in s, the NumberStyles::AllowHexSpecifier style value means that the individual numeric characters in s are always interpreted as hexadecimal characters. Valid hexadecimal characters are 0-9, A-F, and a-f. A prefix such as "0x" is not supported and causes the parse operation to fail. The only other flags that can be combined with the style parameter are NumberStyles::AllowLeadingWhite and NumberStyles::AllowTrailingWhite. (The NumberStyles enumeration includes a composite number style, NumberStyles::HexNumber, that includes both white-space flags.)

Note |
---|

If s is the string representation of a hexadecimal number, it cannot be preceded by any decoration (such as 0x or &h) that differentiates it as a hexadecimal number. This causes the conversion to fail. |

The s parameter is parsed by using the formatting information in a NumberFormatInfo object that is initialized for the current system culture. To specify the culture whose formatting information is used for the parse operation, call the Parse(String, NumberStyles, IFormatProvider) overload.

The following example tries to parse each element in a string array by using a number of NumberStyles values.