vlink::Helpers Namespace Reference

Stateless string, number, hash and formatting helper functions. More...

Functions
VLINK_EXPORT int	to_int (const std::string &str, int dv=0) noexcept
	Converts a decimal string to int.
VLINK_EXPORT int64_t	to_long (const std::string &str, int64_t dv=0, int offset=0) noexcept
	Converts a decimal string to int64_t with an optional byte offset.
VLINK_EXPORT std::string	double_to_string (double value, int precision=2) noexcept
	Converts a double to a string with a specified number of decimal places.
VLINK_EXPORT uint64_t	hash_combine (uint64_t a, uint64_t b) noexcept
	Combines two 64-bit hash values into one using a mixing function.
VLINK_EXPORT void	replace_string (std::string &str, const std::string &from, const std::string &to) noexcept
	Replaces all occurrences of from in str with to in-place.
VLINK_EXPORT std::string	trim_string (const std::string &str) noexcept
	Strips leading and trailing whitespace from a string.
VLINK_EXPORT std::wstring	string_to_wstring (const std::string &input) noexcept
	Converts a UTF-8 std::string to a std::wstring.
VLINK_EXPORT std::string	wstring_to_string (const std::wstring &input) noexcept
	Converts a std::wstring to a UTF-8 std::string.
VLINK_EXPORT std::string	string_local_to_utf8 (const std::string &local_str) noexcept
	Converts a locally-encoded string to UTF-8.
VLINK_EXPORT std::string	string_utf8_to_local (const std::string &utf8_str) noexcept
	Converts a UTF-8 string to the locally-encoded system string.
VLINK_EXPORT std::string	path_to_string (const std::filesystem::path &path) noexcept
	Converts a std::filesystem::path to a UTF-8 std::string portably.
VLINK_EXPORT std::vector< std::string >	get_split_string (const std::string &str, char f) noexcept
	Splits a string by a delimiter character and returns the parts as a vector.
VLINK_EXPORT std::vector< std::string_view >	get_split_string_view (std::string_view str, char f) noexcept
	Splits a string_view by a delimiter character returning non-owning views.
VLINK_EXPORT std::pair< std::string, std::string >	get_pair_string (const std::string &str, char f) noexcept
	Splits a string at the first occurrence of a delimiter and returns a pair.
VLINK_EXPORT std::pair< std::string_view, std::string_view >	get_pair_string_view (std::string_view str, char f) noexcept
	Splits a string_view at the first occurrence of a delimiter returning non-owning views.
VLINK_EXPORT uint32_t	get_hash_code (const std::string &str) noexcept
	Computes a 32-bit FNV-1a-style hash code for a string.
VLINK_EXPORT std::string	format_milliseconds (int64_t milliseconds, bool show_millis) noexcept
	Formats a duration in milliseconds as a human-readable time string.
VLINK_EXPORT std::string	format_date (int64_t nanoseconds_since_epoch) noexcept
	Formats a nanosecond-precision epoch timestamp as a date-time string.
VLINK_EXPORT std::string	format_time_diff (int32_t milliseconds) noexcept
	Formats a time difference in milliseconds as a human-readable string.
VLINK_EXPORT std::string	format_hex_number (int64_t hex_number) noexcept
	Formats a signed 64-bit integer as a "0x..." hexadecimal string.
VLINK_EXPORT std::string	format_hex_number (uint64_t hex_number) noexcept
	Formats an unsigned 64-bit integer as a "0x..." hexadecimal string.
VLINK_EXPORT std::string	format_file_size (size_t size) noexcept
	Formats a byte count as a human-readable size string.
VLINK_EXPORT std::string	format_rate_size (size_t size) noexcept
	Formats a byte-per-second rate as a human-readable string.
VLINK_EXPORT int64_t	convert_date_to_timestamp (const std::string &date) noexcept
	Converts a date string to a Unix millisecond timestamp.
template<uint8_t SizeT>
bool	has_startwith (const std::string &str, const char(&target)[SizeT]) noexcept
	Compile-time check whether str starts with the literal target.
template<uint8_t SizeT>
bool	has_endwith (const std::string &str, const char(&target)[SizeT]) noexcept
	Compile-time check whether str ends with the literal target.
constexpr bool	has_startwith (std::string_view str, std::string_view target) noexcept
	Checks whether a string_view starts with a given prefix (constexpr-friendly).
constexpr bool	has_endwith (std::string_view str, std::string_view target) noexcept
	Checks whether a string_view ends with a given suffix (constexpr-friendly).
constexpr bool	contains_substring (std::string_view sv, std::string_view needle) noexcept
	Checks whether a string_view contains a given substring.

Detailed Description

Stateless string, number, hash and formatting helper functions.

Function Documentation

contains_substring()

bool vlink::Helpers::contains_substring ( std::string_view sv, std::string_view needle )

inlinenodiscardconstexprnoexcept

Checks whether a string_view contains a given substring.

Parameters

sv	String to search.
needle	Substring to find.

Returns

true if sv contains needle. Returns true if needle is empty.

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convert_date_to_timestamp()

VLINK_EXPORT int64_t vlink::Helpers::convert_date_to_timestamp ( const std::string & date )

nodiscardnoexcept

Converts a date string to a Unix millisecond timestamp.

Accepts ISO 8601 style dates such as "2026-03-18" or "2026-03-18 12:00:00".

Parameters

date	Date string to parse.

Returns

Unix timestamp in milliseconds, or -1 on parse failure.

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double_to_string()

VLINK_EXPORT std::string vlink::Helpers::double_to_string ( double value, int precision = 2 )

nodiscardnoexcept

Converts a double to a string with a specified number of decimal places.

Parameters

value	Value to convert.
precision	Number of decimal places. Default: 2.

Returns

Formatted string representation.

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format_date()

VLINK_EXPORT std::string vlink::Helpers::format_date ( int64_t nanoseconds_since_epoch )

nodiscardnoexcept

Formats a nanosecond-precision epoch timestamp as a date-time string.

Output format: "YYYY-MM-DD HH:MM:SS.mmm".

Parameters

nanoseconds_since_epoch

Unix timestamp in nanoseconds.

Returns

Formatted date-time string.

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format_file_size()

VLINK_EXPORT std::string vlink::Helpers::format_file_size ( size_t size )

nodiscardnoexcept

Formats a byte count as a human-readable size string.

Selects the appropriate unit (B, KB, MB, GB, TB) and formats to 2 decimal places. Example: 1536 -> "1.50KB".

Parameters

size	Size in bytes.

Returns

Human-readable size string.

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format_hex_number() [1/2]

VLINK_EXPORT std::string vlink::Helpers::format_hex_number ( int64_t hex_number )

nodiscardnoexcept

Formats a signed 64-bit integer as a "0x..." hexadecimal string.

Parameters

hex_number

Value to format.

Returns

Hexadecimal string prefixed with "0x".

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format_hex_number() [2/2]

VLINK_EXPORT std::string vlink::Helpers::format_hex_number ( uint64_t hex_number )

nodiscardnoexcept

Formats an unsigned 64-bit integer as a "0x..." hexadecimal string.

Parameters

hex_number

Value to format.

Returns

Hexadecimal string prefixed with "0x".

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format_milliseconds()

VLINK_EXPORT std::string vlink::Helpers::format_milliseconds ( int64_t milliseconds, bool show_millis )

nodiscardnoexcept

Formats a duration in milliseconds as a human-readable time string.

Example: 125000 ms -> "00:02:05" or "00:02:05:000" when show_millis is true.

Parameters

milliseconds	Duration in milliseconds.
show_millis	If true, append the sub-second milliseconds component.

Returns

Human-readable time string.

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format_rate_size()

VLINK_EXPORT std::string vlink::Helpers::format_rate_size ( size_t size )

nodiscardnoexcept

Formats a byte-per-second rate as a human-readable string.

Selects the appropriate unit (B/s, KB/s, MB/s, GB/s) and formats to 2 decimal places. Example: 1048576 -> "1.00MB/s".

Parameters

size	Rate in bytes per second.

Returns

Human-readable rate string.

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format_time_diff()

VLINK_EXPORT std::string vlink::Helpers::format_time_diff ( int32_t milliseconds )

nodiscardnoexcept

Formats a time difference in milliseconds as a human-readable string.

Produces strings such as "01:23:45:000" or "00:00:00:250".

Parameters

milliseconds

Time difference in milliseconds.

Returns

Human-readable time-diff string.

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get_hash_code()

VLINK_EXPORT uint32_t vlink::Helpers::get_hash_code ( const std::string & str )

nodiscardnoexcept

Computes a 32-bit FNV-1a-style hash code for a string.

Parameters

str	Input string.

Returns

32-bit hash value.

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get_pair_string()

VLINK_EXPORT std::pair< std::string, std::string > vlink::Helpers::get_pair_string ( const std::string & str, char f )

nodiscardnoexcept

Splits a string at the first occurrence of a delimiter and returns a pair.

Returns {"", ""} if the delimiter is not found.

Parameters

str	Input string.
f	Delimiter character.

Returns

Pair of the left and right substrings around the first delimiter.

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get_pair_string_view()

VLINK_EXPORT std::pair< std::string_view, std::string_view > vlink::Helpers::get_pair_string_view ( std::string_view str, char f )

nodiscardnoexcept

Splits a string_view at the first occurrence of a delimiter returning non-owning views.

Each element is a string_view into the original str. The caller must ensure str outlives all returned views. Returns {"", ""} if str is empty. If the delimiter is not found, the entire string is returned as first with an empty second.

Parameters

str	Input string view.
f	Delimiter character.

Returns

Pair of string_view over the left and right substrings around the first delimiter.

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get_split_string()

VLINK_EXPORT std::vector< std::string > vlink::Helpers::get_split_string ( const std::string & str, char f )

nodiscardnoexcept

Splits a string by a delimiter character and returns the parts as a vector.

Parameters

str	Input string.
f	Delimiter character.

Returns

Vector of substrings (may include empty strings for consecutive delimiters).

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get_split_string_view()

VLINK_EXPORT std::vector< std::string_view > vlink::Helpers::get_split_string_view ( std::string_view str, char f )

nodiscardnoexcept

Splits a string_view by a delimiter character returning non-owning views.

Each element is a string_view into the original str. The caller must ensure str outlives all returned views.

Parameters

str	Input string view.
f	Delimiter character.

Returns

Vector of string_view over the substrings.

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has_endwith() [1/2]

template<uint8_t SizeT>

bool vlink::Helpers::has_endwith ( const std::string & str, const char(&) target[SizeT] )

inlinenodiscardnoexcept

Compile-time check whether str ends with the literal target.

Template Parameters

SizeT

Size of the string literal target (deduced; includes null terminator).

Parameters

str	String to test.
target	String literal suffix to check for.

Returns

true if str ends with target.

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has_endwith() [2/2]

bool vlink::Helpers::has_endwith ( std::string_view str, std::string_view target )

inlinenodiscardconstexprnoexcept

Checks whether a string_view ends with a given suffix (constexpr-friendly).

Falls back to std::string_view::ends_with on C++20; otherwise uses manual comparison.

Parameters

str	String to test.
target	Suffix to check for.

Returns

true if str ends with target.

has_startwith() [1/2]

template<uint8_t SizeT>

bool vlink::Helpers::has_startwith ( const std::string & str, const char(&) target[SizeT] )

inlinenodiscardnoexcept

Compile-time check whether str starts with the literal target.

Details.

Template Parameters

SizeT

Size of the string literal target (deduced; includes null terminator).

Parameters

str	String to test.
target	String literal prefix to check for.

Returns

true if str begins with target.

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has_startwith() [2/2]

bool vlink::Helpers::has_startwith ( std::string_view str, std::string_view target )

inlinenodiscardconstexprnoexcept

Checks whether a string_view starts with a given prefix (constexpr-friendly).

Falls back to std::string_view::starts_with on C++20; otherwise uses manual comparison.

Parameters

str	String to test.
target	Prefix to check for.

Returns

true if str starts with target.

hash_combine()

VLINK_EXPORT uint64_t vlink::Helpers::hash_combine ( uint64_t a, uint64_t b )

nodiscardnoexcept

Combines two 64-bit hash values into one using a mixing function.

Based on a Murmur-inspired mix to spread entropy across both inputs. Suitable for building composite hash keys.

Parameters

a	First hash value.
b	Second hash value.

Returns

Combined hash value.

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path_to_string()

VLINK_EXPORT std::string vlink::Helpers::path_to_string ( const std::filesystem::path & path )

nodiscardnoexcept

Converts a std::filesystem::path to a UTF-8 std::string portably.

On Windows, path::string() returns the ANSI path. This function always returns a UTF-8 string regardless of platform.

Parameters

path	File-system path.

Returns

UTF-8 path string.

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replace_string()

VLINK_EXPORT void vlink::Helpers::replace_string ( std::string & str, const std::string & from, const std::string & to )

noexcept

Replaces all occurrences of from in str with to in-place.

Parameters

str	String to modify.
from	Substring to search for.
to	Replacement substring.

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string_local_to_utf8()

VLINK_EXPORT std::string vlink::Helpers::string_local_to_utf8 ( const std::string & local_str )

nodiscardnoexcept

Converts a locally-encoded string to UTF-8.

On POSIX, uses the current locale's iconv to convert from the system encoding. On Windows, reads the active ANSI code page and converts via Win32 APIs.

Parameters

local_str

Locally-encoded (system locale) string.

Returns

UTF-8 encoded string, or the original string if conversion is not needed.

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string_to_wstring()

VLINK_EXPORT std::wstring vlink::Helpers::string_to_wstring ( const std::string & input )

nodiscardnoexcept

Converts a UTF-8 std::string to a std::wstring.

Parameters

input

UTF-8 encoded string.

Returns

Wide-character string, or empty on failure.

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string_utf8_to_local()

VLINK_EXPORT std::string vlink::Helpers::string_utf8_to_local ( const std::string & utf8_str )

nodiscardnoexcept

Converts a UTF-8 string to the locally-encoded system string.

Parameters

utf8_str

UTF-8 encoded string.

Returns

Locally-encoded (system locale) string.

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to_int()

VLINK_EXPORT int vlink::Helpers::to_int ( const std::string & str, int dv = 0 )

nodiscardnoexcept

Converts a decimal string to int.

Parameters

str	Decimal integer string.
dv	Default value returned when conversion fails. Default: 0.

Returns

Parsed integer, or dv on failure.

to_long()

VLINK_EXPORT int64_t vlink::Helpers::to_long ( const std::string & str, int64_t dv = 0, int offset = 0 )

nodiscardnoexcept

Converts a decimal string to int64_t with an optional byte offset.

Parameters

str	Decimal integer string.
dv	Default value returned when conversion fails. Default: 0.
offset	Starting character offset within str. Default: 0.

Returns

Parsed 64-bit integer, or dv on failure.

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trim_string()

VLINK_EXPORT std::string vlink::Helpers::trim_string ( const std::string & str )

nodiscardnoexcept

Strips leading and trailing whitespace from a string.

Parameters

str	Input string.

Returns

Trimmed copy.

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wstring_to_string()

VLINK_EXPORT std::string vlink::Helpers::wstring_to_string ( const std::wstring & input )

nodiscardnoexcept

Converts a std::wstring to a UTF-8 std::string.

Parameters

input

Wide-character string.

Returns

UTF-8 encoded string, or empty on failure.

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