Regex - count all numbers - c++

Question

I'm looking for a regex pattern that returns true if found 7 numbers on given string. There's no order so if a string is set to: "100 my, str1ng y000" it catches that.

Answer 1

RegEx alone won't count exact occurrences for you, it would return true even if there are more than 7 digits in the string because it would try to find out at least 7 digits in the string.
You can use below code to test exact number (7 in your case) of digits in any string:
var temp = "100 my, str1ng y000 3c43fdgd";
var count = (temp.match(/\d/g) || []).length;
alert(count == 7);

Answer 2

I will show you an C++ Example that
Shows a regex for extracting digit groups
Shows a regex for matching at least 7 digits
Shows, if there is a match for the requested predicate
Shows the number of digits in the string (no regex needed)
Shows the group of digits
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <regex>
// Our test data (raw string). So, containing also \" and so on
std::string testData("100 my, str1ng y000");
std::regex re1(R"#((\d+))#"); // For extracting digit groups
std::regex re2(R"#((\d.*){7,})#"); // For regex match
int main(void)
{
// Define the variable id as vector of string and use the range constructor to read the test data and tokenize it
std::vector<std::string> id{ std::sregex_token_iterator(testData.begin(), testData.end(), re1, 1), std::sregex_token_iterator() };
// Match the regex. Should have at least 7 digits somewhere
std::smatch base_match;
bool containsAtLeast7Digits = std::regex_match(testData, base_match, re2);
// Show result on screen
std::cout << "\nEvaluating string '" << testData <<
"'\n\nThe predicate 'contains-at-leats-7-digits' is " << std::boolalpha << containsAtLeast7Digits <<
"\n\nIt contains overall " <<
std::count_if(
testData.begin(),
testData.end(),
[](const char c) {
return std::isdigit(static_cast<int>(c));
}
) << " digits and " << id.size() << " digit groups. These are:\n\n";
// Print complete vector to std::cout
std::copy(id.begin(), id.end(), std::ostream_iterator<std::string>(std::cout, "\n"));
return 0;
}
Please note: Use std::count for counting. Faster and easier.
Hope this helps . . .