public member function
<regex>
unsigned mark_count() const;
Return number of marked sub-expressions
Returns the number of explicitly marked sub-expressions in the basic_regex.
This corresponds to the number of sub-expressions that should be captured in a match_results object used with this basic_regex object, but without including the eventual match of the whole expression (only the in-parentheses sub-expressions are counted).
Return value
The number of marked sub-expressions.
Example
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// basic_regex::mark_count
// note: using regex, a standard alias of basic_regex<char>
#include <iostream>
#include <regex>
int main ()
{
std::regex myregex ("(sub)([a-z]*).*");
std::cout << "The pattern captures " << myregex.mark_count() << " sub-expressions.\n";
std::cmatch m;
regex_match ("subject", m, myregex);
if ( m.size() == myregex.mark_count() + 1 ) {
std::cout << "Ok, all sub-expressions captured.\n";
std::cout << "Matched expression: " << m[0] << "\n";
for (unsigned i=1; i<m.size(); ++i)
std::cout << "Sub-expression " << i << ": " << m[i] << "\n";
}
return 0;
}
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Output:
The pattern captures 2 sub-expressions.
Ok, all sub-expressions captured.
Matched expression: subject
Sub-expression 1: sub
Sub-expression 2: ject
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