C++ 判断一个大字符串里出现一个小字符串的次数 string对象

Question

C++ 如何判断一个大字符串里出现一个小字符串的次数 用string对象的自带函数有吗

Answer 1

Encapsulate the find method.

Handwritten sample code for reference only:

cppstd::string str("abcabdabcdsdabcds");

auto occurrences = [&str](const std::string &dest) {
    size_t pos, pre = 0, count = 0;
    while ( (pos = str.find(dest, pre)) != std::string::npos ) {
        ++count;
        pre = pos + 1;
    }
    return count;
};

std::cout << occurrences("abc") << std::endl;

Answer 2

Write an example, such as the number of times abc appears in abcabcabcdsadg

Answer 3

It can be processed using KMP algorithm or Sunday algorithm