basic_regex::assign

Article
12/01/2015

Assigns a value to the regular expressoin object.

Syntax

basic_regex& assign(
    const basic_regex& right
);
basic_regex& assign(
    const Elem* ptr,
    flag_type flags = ECMAScript
);
basic_regex& assign(
    const Elem* ptr, 
    size_type len,
    flag_type flags = ECMAScript
);
basic_regex& assign(
    initializer_list<_Elem> IList,
    flag_type flags = regex_constants::ECMAScript
);
template<class STtraits, class STalloc>
    basic_regex& assign(
        const basic_string<Elem, STtraits, STalloc>& str,
        flag_type flags = ECMAScript
    );
template<class InIt>
    basic_regex& assign(
        InIt first,         InIt last,
        flag_type flags = ECMAScript
    );

Parameters

STtraits
Traits class for a string source.
STalloc
Allocator class for a string source.
InIt
Input iterator type for a range source.
right
Regex source to copy.
ptr
Pointer to beginning of sequence to copy.
flags
Syntax option flags to add while copying.
len/TD>
Length of sequence to copy.
str
String to copy.
first
Beginning of sequence to copy.
last
End of sequence to copy.
IList
The initializer_list to copy.

Remarks

The member functions each replace the regular expression held by *this with the regular expression described by the operand sequence, then return *this.

Example

// std_tr1__regex__basic_regex_assign.cpp 
// compile with: /EHsc 
#include <regex> 
#include <iostream> 

using namespace std;

int main()
{
    regex::value_type elem = 'x';
    regex::flag_type flag = regex::grep;

    elem = elem;  // to quiet "unused" warnings 
    flag = flag;

    // constructors 
    regex rx0;
    cout << "match(\"abc\", \"\") == " << boolalpha
        << regex_match("abc", rx0) << endl;

    regex rx1("abcd", regex::ECMAScript);
    cout << "match(\"abc\", \"abcd\") == " << boolalpha
        << regex_match("abc", rx1) << endl;

    regex rx2("abcd", 3);
    cout << "match(\"abc\", \"abc\") == " << boolalpha
        << regex_match("abc", rx2) << endl;

    regex rx3(rx2);
    cout << "match(\"abc\", \"abc\") == " << boolalpha
        << regex_match("abc", rx3) << endl;

    string str("abcd");
    regex rx4(str);
    cout << "match(string(\"abcd\"), \"abc\") == " << boolalpha
        << regex_match("abc", rx4) << endl;

    regex rx5(str.begin(), str.end() - 1);
    cout << "match(string(\"abc\"), \"abc\") == " << boolalpha
        << regex_match("abc", rx5) << endl;
    cout << endl;

    // assignments 
    rx0 = "abc";
    rx0 = rx1;
    rx0 = str;

    rx0.assign("abcd", regex::ECMAScript);
    rx0.assign("abcd", 3);
    rx0.assign(rx1);
    rx0.assign(str);
    rx0.assign(str.begin(), str.end() - 1);

    rx0.swap(rx1);

    // mark_count 
    cout << "\"abc\" mark_count == "
        << regex("abc").mark_count() << endl;
    cout << "\"(abc)\" mark_count == "
        << regex("(abc)").mark_count() << endl;

    // locales 
    regex::locale_type loc = rx0.imbue(locale());
    cout << "getloc == imbued == " << boolalpha
        << (loc == rx0.getloc()) << endl;

    // initializer_list
    regex rx6({ 'a', 'b', 'c' }, regex::ECMAScript);
    cout << "match(\"abc\") == " << boolalpha
        << regex_match("abc", rx6);
    cout << endl; 
}

match("abc", "") == falsematch("abc", "abcd") == falsematch("abc", "abc") == truematch("abc", "abc") == truematch(string("abcd"), "abc") == falsematch(string("abc"), "abc") == true"abc" mark_count == 0"(abc)" mark_count == 1getloc == imbued == truematch("abc") == true

Requirements

Header: <regex>

Namespace: std