CPP

find all occurrences of a substring in a string c++

#include <string>
#include <iostream>

using namespace std;

int main()
{
    string s("hello hello");
    int count = 0;
    size_t nPos = s.find("hello", 0); // first occurrence
    while(nPos != string::npos)
    {
        count++;
        nPos = s.find("hello", nPos + 1);
    }

    cout << count;
};

cpp string find all occurence

string str,sub; // str is string to search, sub is the substring to search for

vector<size_t> positions; // holds all the positions that sub occurs within str

size_t pos = str.find(sub, 0);
while(pos != string::npos)
{
    positions.push_back(pos);
    pos = str.find(sub,pos+1);
}

find no of occurences of each letter in string c++

void countCharImproved(char *str) {
    std::map<char, int> count;
    int l = strlen(str);
    for(int i=0; i<l; i++) {
        count[str[i]]++;
    }
    for(const auto kvp : count) {
        std::cout << kvp.first << " occurs " << kvp.second << " times
";
    }
}