std::to_string

 

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basic_string

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std::basic_string

Member functions basic_string::basic_string basic_string::~basic_string basic_string::operator= basic_string::assign basic_string::assign_range (C++23) basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (DR*) basic_string::back (DR*) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) 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 (DR*) Modifiers basic_string::clear basic_string::insert basic_string::insert_range (C++23) basic_string::erase basic_string::push_back basic_string::pop_back (DR*) basic_string::append basic_string::append_range (C++23) basic_string::operator+= basic_string::replace basic_string::replace_with_range (C++23) basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23)   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 Operations basic_string::compare basic_string::starts_with (C++20) basic_string::ends_with (C++20) basic_string::contains (C++23) basic_string::substr Constants basic_string::npos Non-member functions operator+ swap(std::basic_string) erase(std::basic_string)erase_if(std::basic_string) (C++20)(C++20) I/O operator<<operator>> getline Comparison operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) Numeric conversions 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) Literals operator""s (C++14) Helper classes hash<std::basic_string> (C++11) Deduction guides (C++17)

 

Defined in header <string>
std::string to_string( int value );	(1)	(since C++11)
std::string to_string( long value );	(2)	(since C++11)
std::string to_string( long long value );	(3)	(since C++11)
std::string to_string( unsigned value );	(4)	(since C++11)
std::string to_string( unsigned long value );	(5)	(since C++11)
std::string to_string( unsigned long long value );	(6)	(since C++11)
std::string to_string( float value );	(7)	(since C++11)
std::string to_string( double value );	(8)	(since C++11)
std::string to_string( long double value );	(9)	(since C++11)

Converts a numeric value to std::string.

1) Converts a signed integer to a string with the same content as what

std::sprintf(buf, "%d", value) would produce for sufficiently large buf.

2) Converts a signed integer to a string with the same content as what

std::sprintf(buf, "%ld", value) would produce for sufficiently large buf.

3) Converts a signed integer to a string with the same content as what

std::sprintf(buf, "%lld", value) would produce for sufficiently large buf.

4) Converts an unsigned integer to a string with the same content as what

std::sprintf(buf, "%u", value) would produce for sufficiently large buf.

5) Converts an unsigned integer to a string with the same content as what

std::sprintf(buf, "%lu", value) would produce for sufficiently large buf.

6) Converts an unsigned integer to a string with the same content as what

std::sprintf(buf, "%llu", value) would produce for sufficiently large buf.

7,8) Converts a floating point value to a string with the same content as what

std::sprintf(buf, "%f", value) would produce for sufficiently large buf.

9) Converts a floating point value to a string with the same content as what

std::sprintf(buf, "%Lf", value) would produce for sufficiently large buf.

Parameters

value

-

a numeric value to convert

Return value

a string holding the converted value

Exceptions

May throw std::bad_alloc from the std::string constructor.

Notes

• With floating point types std::to_string may yield unexpected results as the number of significant digits in the returned string can be zero, see the example.
• The return value may differ significantly from what std::cout prints by default, see the example.
• std::to_string relies on the current locale for formatting purposes, and therefore concurrent calls to std::to_string from multiple threads may result in partial serialization of calls. C++17 provides std::to_chars as a higher-performance locale-independent alternative.

Example

Run this code

#include <iostream>
#include <string>
 
int main() 
{
    double f = 23.43;
    double f2 = 1e-9;
    double f3 = 1e40;
    double f4 = 1e-40;
    double f5 = 123456789;
    std::string f_str = std::to_string(f);
    std::string f_str2 = std::to_string(f2); // Note: returns "0.000000"
    std::string f_str3 = std::to_string(f3); // Note: Does not return "1e+40".
    std::string f_str4 = std::to_string(f4); // Note: returns "0.000000"
    std::string f_str5 = std::to_string(f5);
    std::cout << "std::cout: " << f << '\n'
              << "to_string: " << f_str  << "\n\n"
              << "std::cout: " << f2 << '\n'
              << "to_string: " << f_str2 << "\n\n"
              << "std::cout: " << f3 << '\n'
              << "to_string: " << f_str3 << "\n\n"
              << "std::cout: " << f4 << '\n'
              << "to_string: " << f_str4 << "\n\n"
              << "std::cout: " << f5 << '\n'
              << "to_string: " << f_str5 << '\n';
}

Output:

std::cout: 23.43
to_string: 23.430000
 
std::cout: 1e-09
to_string: 0.000000
 
std::cout: 1e+40
to_string: 10000000000000000303786028427003666890752.000000
 
std::cout: 1e-40
to_string: 0.000000
 
std::cout: 1.23457e+08
to_string: 123456789.000000

See also

to_wstring (C++11)	converts an integral or floating-point value to wstring (function)
stoulstoull (C++11)(C++11)	converts a string to an unsigned integer (function)
stoistolstoll (C++11)(C++11)(C++11)	converts a string to a signed integer (function)
stofstodstold (C++11)(C++11)(C++11)	converts a string to a floating point value (function)
to_chars (C++17)	converts an integer or floating-point value to a character sequence (function)