I have a vector
containing strings
that follow the format of text_number-number
Eg: Example_45-3
The 'best' way to do this in C++11 and later is probably using regular expressions, which combine high expressiveness and high performance when the test is repeated often enough.
The following code demonstrates the basics. You should #include
for it to work.
// The example inputs
std::vector inputs {
"Example_0-0", "Example_0-1", "Example_0-2", "Example_0-3", "Example_0-4",
"Example_1-0", "Example_1-1", "Example_1-2", "Example_1-3", "Example_1-4"
};
// The regular expression. A lot of the cost is incurred when building the
// std::regex object, but when it's reused a lot that cost is amortised.
std::regex imgNumRegex { "^[^_]+_([[:digit:]]+)-([[:digit:]]+)$" };
for (const auto &input: inputs){
// This wil contain the match results. Parts of the regular expression
// enclosed in parentheses will be stored here, so in this case: both numbers
std::smatch matchResults;
if (!std::regex_match(input, matchResults, imgNumRegex)) {
// Handle failure to match
abort();
}
// Note that the first match is in str(1). str(0) contains the whole string
std::string theFirstNumber = matchResults.str(1);
std::string theSecondNumber = matchResults.str(2);
std::cout << "The input had numbers " << theFirstNumber;
std::cout << " and " << theSecondNumber << std::endl;
}