std::strxfrm

 

C++

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Technical Specifications

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

char_traits

 

Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C++11)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to numeric formats
atof atoiatolatoll strtolstrtoll	strtoulstrtoull strtofstrtodstrtold strtoimaxstrtouimax (C++11)(C++11)
String manipulation
strcpy
strncpy
strcat
strncat
strxfrm
String examination
strlen strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtok
Memory manipulation
memchr
memcmp
memset
memcpy
memmove
Miscellaneous
strerror

 

Defined in header <cstring>
std::size_t strxfrm( char* dest, const char* src, std::size_t count );

Transforms the null-terminated byte string pointed to by src into the implementation-defined form such that comparing two transformed strings with std::strcmp gives the same result as comparing the original strings with std::strcoll, in the current C locale.

The first count characters of the transformed string are written to destination, including the terminating null character, and the length of the full transformed string is returned, excluding the terminating null character.

If count is ​0​, then dest is allowed to be a null pointer.

Notes

The correct length of the buffer that can receive the entire transformed string is 1+std::strxfrm(nullptr, src, 0)

Parameters

dest	-	pointer to the first element of the array where the transformed string will be written
src	-	pointer to the first character of a null-terminated byte string to transform
count	-	maximum number of characters to be written

Return value

The length of the transformed string, not including the terminating null-character.

Example

Run this code

#include <iostream>
#include <iomanip>
#include <cstring>
#include <string>
 
int main()
{
    std::setlocale(LC_COLLATE, "cs_CZ.iso88592");
 
    std::string in1 = "hrnec";
    std::string out1(1+std::strxfrm(nullptr, in1.c_str(), 0), ' ');
    std::string in2 = "chrt";
    std::string out2(1+std::strxfrm(nullptr, in2.c_str(), 0), ' ');
 
    std::strxfrm(&out1[0], in1.c_str(), out1.size());
    std::strxfrm(&out2[0], in2.c_str(), out2.size());
 
    std::cout << "In the Czech locale: ";
    if(out1 < out2)
         std::cout << in1 << " before " << in2 << '\n';
    else
         std::cout << in2 << " before " << in1 << '\n';
 
    std::cout << "In lexicographical comparison: ";
    if(in1 < in2)
         std::cout << in1 << " before " << in2 << '\n';
    else
         std::cout << in2 << " before " << in1 << '\n';
 
}

Output:

In the Czech locale: hrnec before chrt
In lexicographical comparison: chrt before hrnec

See also

wcsxfrm	transform a wide string so that wcscmp would produce the same result as wcscoll (function)
do_transform [virtual]	transforms a string so that collation can be replaced by comparison (virtual protected member function of std::collate)
strcoll	compares two strings in accordance to the current locale (function)
C documentation for strxfrm