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std::regex_search can be used to find whether a regular expression matches in a string. 1. It returns a boolean value to indicate whether a match is found; 2. It can be combined with std::smatch to get the matching content and location; 3. Use std::sregex_iterator to traverse all matches; 4. It is often used for pattern matching and text extraction such as mailboxes and phones; 5. Pay attention to the differences in regular support of different compilers. The complete example shows the process of finding and outputting all email addresses, and the result shows two matches correctly.
std::regex_search is a function in C used to find whether a regular expression matches in a string, and is defined in the <regex></regex> header file. It returns a boolean value indicating whether a match is found, and can also extract the matching substring with std::smatch .
Here is a practical std::regex_search example showing how to find an email address:
#include <iostream>
#include <string>
#include <regex>
int main() {
std::string text = "Contact us at support@example.com or sales@company.org for help.";
// Define a regular expression that matches the mailbox std::regex email_pattern(R"(\b[a-zA-Z0-9._% -] @[a-zA-Z0-9.-] \.[a-zA-Z]{2,}\b)");
std::smatch match;
// Use regex_search to find the first matching mailbox if (std::regex_search(text, match, email_pattern)) {
std::cout << "Finish the first email address: " << match.str() << std::endl;
std::cout << "Position: " << match.position() << std::endl;
} else {
std::cout << "Emailbox not found" << std::endl;
}
// Find and print all matching mailboxes std::sregex_iterator next(text.begin(), text.end(), email_pattern);
std::sregex_iterator end;
int count = 1;
while (next != end) {
std::smatch current_match = *next;
std::cout << "mailbox" << count << ": " << current_match.str() << std::endl;
next ;
}
return 0;
}Output result:
Find the first email address: support@example.com Location: 13 Email 1: support@example.com Email 2: sales@company.org
Key points description:
-
std::regex: Compile regular expression pattern. -
std::smatch: Save the matching results, including the entire match and capture group. -
std::regex_search(text, match, pattern): Search for substrings matchingpatternintext. If found,matchsaves the result. -
std::sregex_iterator: used to traverse all matches and is suitable for finding multiple results.
Common usage scenarios:
- Verify that there is a pattern in the string (such as phone number, email).
- Extract specific information from the text.
- Text processing tasks such as log analysis, data cleaning, etc.
Note: C regular support varies from compiler to compiler, it is recommended to use newer versions of GCC or Clang. MSVC also supports it, but some complex regularities may behave differently.
Basically all is it, not complicated but it is easy to ignore details.
The above is the detailed content of C std::regex_search example. For more information, please follow other related articles on the PHP Chinese website!
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