how to count the number of occurrences of a string in a string in c++ code example

Example 1: count a character in a string c++

count(str.begin(), str.end(), 'e')

Example 2: string count occurrences c++

#include <algorithm>

std::string s = "a_b_c";
size_t n = std::count(s.begin(), s.end(), '_'); //n=2

Example 3: count occurrences of character in string c++

std::string s = "a_b_c";
size_t n = std::count(s.begin(), s.end(), '_'); // n=2