Cpp int to wstring

std:: to_string

Let buf be an internal to the conversion functions buffer, sufficiently large to contain the result of conversion.

Contents

[edit] Parameters

[edit] Return value

A string holding the converted value.

[edit] Exceptions

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

[edit] 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.

[edit] Example

#include #include int main() { for (const double f : {23.43, 1e-9, 1e40, 1e-40, 123456789.0}) std::cout  "std::cout: "  f  '\n'  "to_string: "  std::to_string(f)  "\n\n"; }

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

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std:: to_wstring

Let buf be an internal to the conversion functions buffer, sufficiently large to contain the result of conversion.

1) Converts a signed decimal integer to a wide string as if by std:: swprintf ( buf, sz, L «%d» , value ) .

2) Converts a signed decimal integer to a wide string as if by std:: swprintf ( buf, sz, L «%ld» , value ) .

3) Converts a signed decimal integer to a wide string as if by std:: swprintf ( buf, sz, L «%lld» , value ) .

4) Converts an unsigned decimal integer to a wide string as if by std:: swprintf ( buf, sz, L «%u» , value ) .

5) Converts an unsigned decimal integer to a wide string as if by std:: swprintf ( buf, sz, L «%lu» , value ) .

6) Converts an unsigned decimal integer to a wide string as if by std:: swprintf ( buf, sz, L «%llu» , value ) .

7,8) Converts a floating point value to a wide string as if by std:: swprintf ( buf, sz, L «%f» , value ) .

9) Converts a floating point value to a wide string as if by std:: swprintf ( buf, sz, L «%Lf» , value ) .

Contents

[edit] Parameters

[edit] Return value

A wide string holding the converted value.

[edit] Exceptions

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

[edit] Example

#include #include int main() { for (const double f : {23.43, 1e-9, 1e40, 1e-40, 123456789.0}) std::wcout  "std::wcout: "  f  '\n'  "to_wstring: "  std::to_wstring(f)  "\n\n"; }

std::wcout: 23.43 to_wstring: 23.430000 std::wcout: 1e-09 to_wstring: 0.000000 std::wcout: 1e+40 to_wstring: 10000000000000000303786028427003666890752.000000 std::wcout: 1e-40 to_wstring: 0.000000 std::wcout: 1.23457e+08 to_wstring: 123456789.000000

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std:: to_wstring

Returns a wstring with the representation of val.

The format used is the same that wprintf would print for the corresponding type:

type of val	wprintf equivalent	description
int	L"%d"	Decimal-base representation of val. The representations of negative values are preceded with a minus sign (-).
long	L"%ld"
long long	L"%lld"
unsigned	L"%u"	Decimal-base representation of val.
unsigned long	L"%lu"
unsigned long long	L"%llu"
float	L"%f"	As many digits are written as needed to represent the integral part, followed by the decimal-point character and six decimal digits. inf (or infinity) is used to represent infinity. nan (followed by an optional sequence of characters) to represent NaNs (Not-a-Number). The representations of negative values are preceded with a minus sign (-).
double	L"%f"
long double	L"%Lf"

Parameters

Return Value

Example

// to_wstring example // std::wcout // std::wstring, std::to_wstring int main () < std::wstring pi = L"pi is " + std::to_wstring(3.1415926); std::wstring perfect = std::to_wstring(1+2+4+7+14) + L" is a perfect number"; std::wcout '\n'; std::wcout '\n'; return 0; >

pi is 3.141593 28 is a perfect number 

Exceptions

See also

swprintf Write formatted data to wide string (function) to_string Convert numerical value to string (function)

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std:to_string and std::to_wstring in C++

In this article, we have explored the functions std:to_string and std::to_wstring in C++ STL along with the difference between string and wstring (wide string).

Table of content

In short: std:to_string is used to convert a numeric datatype to string while std::to_wstring is used to convert a numeric datatype to wide string (wstring).

std::to_string

std::to_string in C++ is a Template used to convert any data type to
string.

It can be used on all data types such as:

The syntax used is as follows ::

string to_string(datatype variable name) 

For example conversion of double can be done as follow:

CODE of conversion

#include #include using namespace std; int main() < double a=92.863; char c[10]="hello"; std::string str1 = std::to_string(a); // double a is converted into string std::cout

Now to check wether the data type is converted to string or not we can use
syntax of type id is as follows
typeif(variable name).name();

COMPLEXITY
It is a process which can be converted in O(1) time complexity.

Application
one of the most common appplication used is to find out the index of a particular element in the string after conversion.

#include #include using namespace std; int main() < // Converting number to string std::string str = std::to_string(732); // Finding 7 in the number std::cout

As we can see +1 is added after str.find() because it indexing is starts from 0.

std::to_wstring

This function is used to convert the numerical value to the wide string i.e. it parses a numerical value of datatypes int ,float,char,double to a wide string. In short it converts all data types in w string datatype by typecasting the numeric values stored in it.

Syntax of conversion
Syntax :

wstring to_wstring (int variable name); 

The only input it takes is variable name and as a result it converts the given data to to wstring.

code of conversion

#include #include using namespace std; int main () < float x = 3.1415926; int a = 5 , b = 9; double y = 6.29; // numerical values being typecasted into wstring wstring perfect = to_wstring(a+b) + L" is a number"; wstring num = to_wstring(y/x) + L"is division of two numbers"; // Printing the typecasted wstring wcout 14 is a number 2.002169 is division of two numbers 

To print out come we use wcout instead of cout ,therefore we have to include #include for proper functioning.

Applications
It can be used for calculation to be used in report statement such as average value , we can directly use this function to convert numerical values rather than calculating it.

// These header files contains wcout and wstring #include #include using namespace std; // Driver code int main () < int a = 60 , b = 45; wstring rep = L"Number of section = " + to_wstring(a/b); wstring sec_rep = to_wstring(b) + L" is the number of students in each section"; wcout

number of section is 1 45 is the number of student in the class. 

Difference between string and wstring

• std::string holds collection of char_t (char) to represent a string. The type char strictly holds only the standard ASCII characters (0-255).
• std::wstring holds collection of wchar_t (wide chars)to represent a string. The type wchar_t holds the character in UTF (2/4 bytes) format. They are used to store unicode.

On parallel lines you can differentiate between std::cout & std::wcout, you can understand std::cout cannot work with std::wstring.

With this article at OpenGenus, you must have the complete idea of std:to_string and std::to_wstring in C++.

shivansh chaturvedi

OpenGenus Tech Review Team

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