Changing value in a pair from foreach doesn't show change out of loop

Question

I have an object outside of the for-each loops that contains a static vector of pair. I want to increment the second parameter of the pair, as the code below shows. However, when I print the second parameter from within another for-each loop, it prints '0' as the value for all elements in the vector. But if I print from within the first for-each loop, it prints '1', as intended.

I do not understand why the value would not be saved after the change. I have looked it up and the for-each allows me to change the value, as well as the pair.

char[] name = "abcde"; 
for(int i =0;i<5;i++){
    std::pair <string, int> pairCounter;
    pairCounter = make_pair(name[i], 0);
    outside::lstPairCounter.push_back(pairCounter);
}
for each (pair<string,int> counter in outside::lstPairCounter){

     counter.second++;

 }
for each (pair<string,int> counter in outside::lstPairCounter){

   cout<<counter.second<<'\n';

}

Answer 1

Don't use

for each

preferrably (see https://msdn.microsoft.com/en-us/library/ms177202.aspx), as it is non-standard.

Here's how a for each loop in C++11 works:

std::vector<int> v{1,2,3,4,5};

// i becomes a COPY of each value in v, i.e. no changes occur in v
for(int i : v)
    ++i;

// i becomes a reference to the values in v, changes DO occur in v
for(int& i : v)
    ++i;

// you could also take a const-reference, good for expensive-to-copy types
for(const T& t: other_vector)
    // do stuff

Answer 2

Take element by reference instead of value:

for (std::pair<string,int>& counter : outside::lstPairCounter){
    counter.second++;
}