std::basic_string::substr

 

C++

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Standard library headers

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Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Strings library

Null-terminated strings

Byte strings

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Classes

basic_string

char_traits

 

std::basic_string

Member functions basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (C++11) basic_string::back (C++11) basic_string::data basic_string::c_str Iterators basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (C++11)

Operations basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back (C++11) basic_string::append basic_string::operator+= basic_string::compare basic_string::replace basic_string::substr basic_string::copy basic_string::resize basic_string::swap Search basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Constants basic_string::npos

Non-member functions operator+ operator==operator!=operator<operator>operator<=operator>= swap(std::basic_string) operator<<operator>> getline stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11) stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) Helper classes hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string> (C++11)(C++11)(C++11)(C++11)

 

basic_string substr( size_type pos = 0,                      size_type count = npos ) const;

Returns a substring [pos, pos+count). If the requested substring extends past the end of the string, or if count == npos, the returned substring is [pos, size()).

Parameters

pos	-	position of the first character to include
count	-	length of the substring

Return value

1. An empty string if pos == size().
2. String containing the substring [pos, pos+count).

Exceptions

std::out_of_range if pos > size()

Complexity

Linear in count

Example

Run this code

#include <string>
#include <iostream>
 
int main()
{
    std::string a = "0123456789abcdefghij";
 
    std::string sub1 = a.substr(10);
    std::cout << sub1 << '\n';
 
    std::string sub2 = a.substr(5, 3);
    std::cout << sub2 << '\n';
 
    std::string sub3 = a.substr(12, 100);
    std::cout << sub3 << '\n';
 
    std::string sub4 = a.substr(a.size()-3, 50);
    std::cout << sub4 << '\n';
}

Output:

abcdefghij
567
cdefghij
hij

See also

copy	copies characters (public member function)
sizelength	returns the number of characters (public member function)
find	find characters in the string (public member function)