To ask whether a given input string haystack conforms to a given regex rneedle, you can use std::regex_match(haystack, rneedle). The regex always comes last, which is reminiscent of JavaScript's syntax haystack.match(rneedle) and Perl's haystack =~ rneedle even as it's opposed to Python's re.match(rneedle, haystack). The regex_match function returns true if the regex matches the entire input string, and false otherwise:
std::regex rx("(left|right) ([0-9]+)");
std::string line;
while (std::getline(std::cin, line)) {
if (std::regex_match(line, rx)) {
process_command(line);
} else {
printf("Unrecognized command '%s'.\n",
line.c_str());
}
}
The regex_search function returns true if the regex matches any portion of the input string. Essentially, it just puts ...
