如何检测C ++中是否遇到换行符？

Question

I have input where we get to know that the current testcase has finished and next started by a blank line in between. How can I check that if a blank line has occurred in C++?

Answer 1

There're many ways to detect a blank line (if the line doesn't contain spaces, of course).

Example 1 (it's supposed you're getting your data line by line):

#include <string.h>

...

if (strcmp(yourLine, "") == 0) { // or strcmp(yourLine, "\n"), it depends how you get yourLine in your code above
    // your code
    ...
}

Example 2:

#include <string>

std::string yourData = "qwe\nrty\n\nasd\nfgh\n";

std::size_t index;
while ((index = yourData.find("\n\n")) != std::string::npos) {
    std::string part = yourData.substr(0, index);
    // your code
    yourData = yourData.substr(index);
}

In Example 2 methogs std::string::find and std::string::substr were used. You can look at the documentation for them: http://www.cplusplus.com/reference/string/string/find/ , http://www.cplusplus.com/reference/string/string/substr/

Answer 2

You will need to check for '\\r', '\\n', or "\\r\\n" depending on what OS your code is running on. See Difference between \\n and \\r? for a good explanation on why this is OS-dependent.