Getting bad_alloc on specific inputs while using C++ strings

I am trying to create a basic program to implement Hamming code for my networking class

The program runs correctly for most cases but there are some specific cases where it breaks with -1073741819

The program takes a string of '0's and '1's as input

When the input string is of length of the form odd number ^ 2 an error occurs giving -1073741819 std::bad_alloc

All other cases seem to work
example input of 8 works, 10 works but of 9 doesn't work.
Similarly input of length 24 works, 26 works but 25 doesn't

Below is the code
It includes some code which does not give an error and I have marked when the irrelevant part starts.

#include<iostream>
#include<cmath>
#include<vector>

using namespace std;

int main(){

string data;
cout<<"Enter data to send => :\n";
cin>>data;

int len = data.length();
int maxPowerOfTwo = log2(len-1) + 1;
int totalLength = len +  maxPowerOfTwo + 1;

vector< int > toSend;
toSend.reserve(totalLength);
toSend[0] = 0;

int l = 0;
int k = 0;

for(int i=0;i<totalLength+1;i++){
    if(l==i){
        toSend[i] = 0;
        if(l==0){
            l++;
        }
        else{
            l*=2;
        }
    }
    else{
        toSend[i] = data[k]-48;
        k++;
    }
}

int currentPower = 0;
int startPosition = 1;

for(;currentPower<maxPowerOfTwo+1;currentPower++){
    int tempSum = 0;
    int tempCounter = 0;
    for(int currentPosition = startPosition;currentPosition<totalLength+1;){
        tempSum = tempSum + toSend[currentPosition];
        tempCounter++;
        if(tempCounter==startPosition){
            currentPosition += startPosition + 1;
            tempCounter = 0;
        }
        else{
            currentPosition++;
        }
    }
    if(tempSum%2!=0){
        toSend[startPosition] = 1;
    }
    else{
        toSend[startPosition] = 0;
    }
    startPosition*=2;
}
string finaltoSend;

for(int i=1;i<=totalLength;i++){ // MARKED LOOP
    if(toSend[i]==0){
        finaltoSend.push_back('0');
    }
    else{
        finaltoSend.push_back('1');
    }
}

/*
==== NOT RELEVANT ====

cout<<"\nData to send => "<<finaltoSend<<'\n';
string received = finaltoSend;
cout<<"\nEnter data received of length "<<totalLength<<'\n';
cin>>received;
int t_len = received.length();
int t_maxPowerOfTwo = log2(t_len-1);
int t_currentPower = 0;
int t_startPosition = 1;
int errorAt = -1;
for(;t_currentPower<t_maxPowerOfTwo+1;t_currentPower++){
    int tempSum = 0;
    int tempCounter = 0;
    for(int currentPosition = t_startPosition;currentPosition<t_len+1;){
        tempSum = tempSum + received[currentPosition-1] - 48;
        tempCounter++;
        if(tempCounter==t_startPosition){
            currentPosition += t_startPosition + 1;
            tempCounter = 0;
        }
        else{
            currentPosition++;
        }
    }
    if(tempSum%2!=0){
        errorAt+=t_startPosition;
    }
    t_startPosition*=2;
}
if(errorAt == -1){
    cout<<"\nNo error";
}
else{
    errorAt++;
    cout<<"\n\nError at \n\n"<<errorAt;
}

==== END ====
*/

return 0;
}

While debugging I found that the program breaks in the second iteration of the marked loop

I have tried finaltoSend.append("0") and also reserving memory before hand but none of the options work

Any hints would be greatly appreciated