std::basic_string_view<CharT,Traits>:: starts_with
From cppreference.com
<
cpp
|
string
|
basic string view
|
constexpr
bool
starts_with
(
basic_string_view sv
)
const
noexcept
;
|
(1) | (since C++20) |
|
constexpr
bool
starts_with
(
CharT ch
)
const
noexcept
;
|
(2) | (since C++20) |
|
constexpr
bool
starts_with
(
const
CharT
*
s
)
const
;
|
(3) | (since C++20) |
Checks if the string view begins with the given prefix, where
1)
the prefix is a string view. Effectively returns
basic_string_view
(
data
(
)
,
std::
min
(
size
(
)
, sv.
size
(
)
)
)
==
sv
.
2)
the prefix is a single character. Effectively returns
!
empty
(
)
&&
Traits
::
eq
(
front
(
)
, ch
)
.
3)
the prefix is a null-terminated character string. Effectively returns
starts_with
(
basic_string_view
(
s
)
)
.
Parameters
| sv | - |
a string view which may be a result of implicit conversion from
std::basic_string
|
| ch | - | a single character |
| s | - | a null-terminated character string |
Return value
true if the string view begins with the provided prefix, false otherwise.
Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_starts_ends_with
|
201711L | (C++20) | String prefix and suffix checking: starts_with() and ends_with() |
Example
Run this code
#include <cassert> #include <string_view> int main() { using namespace std::literals; assert ("" // (1) starts_with( basic_string_view ) && "https://cppreference.com"sv.starts_with("http"sv) == true && "https://cppreference.com"sv.starts_with("ftp"sv) == false // (2) starts_with( CharT ) && "C++20"sv.starts_with('C') == true && "C++20"sv.starts_with('J') == false // (3) starts_with( const CharT* ) && std::string_view("string_view").starts_with("string") == true && std::string_view("string_view").starts_with("String") == false ); }
See also
|
(C++20)
|
checks if the string view ends with the given suffix
(public member function) |
|
(C++20)
|
checks if the string starts with the given prefix
(public member function of
std::basic_string<CharT,Traits,Allocator>
)
|
|
(C++20)
|
checks if the string ends with the given suffix
(public member function of
std::basic_string<CharT,Traits,Allocator>
)
|
|
(C++23)
|
checks if the string contains the given substring or character
(public member function of
std::basic_string<CharT,Traits,Allocator>
)
|
|
(C++23)
|
checks if the string view contains the given substring or character
(public member function) |
|
compares two views
(public member function) |