Only able to print entry of an array at most twice [closed] - c++

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When I run the executable containing a function with the following code from the command line result[1] is only printed twice before the program crashes (" *.exe has stopped working ") even though blocklength is set to 25.
When I run the exact same executable with a double click the program crashes without printing anything. (but it runs until right before the for loop)
result is an array of type double and length blocklength, it is passed to the function as an argument.
for (int i = 0; i < blocklength; i++) {
cout << result[1] << endl;
}
When I used the GNU Project Debugger (GDB) to go through the program step by step it printed out result[1] 25 times and did not crash.
Obviously the original for loop did more than just print the same value over and over, but I narrowed the problem down to this and am now totally stuck and confused.
I would really appreciate any help or inputs.
Here's the full code, result is defined in the main function as double* result = new double[blocklength] and immediately passed to the function:
void entropy(char* input, int l_input, double* result, int blocklength, char order)
{
int l_counter = pow(order, blocklength);
int* counter = new int[l_counter];
double prob = 0;
int max_counter = 1;
int* temp = new int[l_input];
for (int i = 0; i < l_input; i++) {
temp[i] = 0;
}
for (int s = 1; s <= blocklength; s++)
{
max_counter *= order;
// reset counter
for (int i = 0; i < max_counter; i++) {
counter[i] = 0;
}
// init result
result[s] = 0;
for (int b = 0; b < l_input + 1 - s; b++) {
temp[b] = order * temp[b] + input[b - 1 + s];
counter[temp[b]]++;
}
for (int b = 0; b < max_counter; b++) {
prob = counter[b] / (double)(l_input - s + 1);
if (prob != 0)
{
result[s - 1] = result[s - 1] + fabs(prob * log(prob));
}
}
std::cout << "Block " << s << " okay" << std::endl;
}
cout << "sum done" << endl;
for (int i = 0; i < blocklength; i++)
{
cout << result[1] << endl;
}
std::cout << "Entroyp done!" << std::endl;
}

Answer 1

There are 2 things that seem wrong with your code.
result[s] is not read/written after it's initialised.
result[s] = 0;
Instead result[s-1] is accessed.
result[s - 1] = result[s - 1] + fabs(prob * log(prob));
This means that result[0] will never be set to 0. This also means that result[blocklength] = 0 will be assigned but never used.
If you have a line like int* result = new int[blocklength]; in your code, then you access a value that isn't in your array at all. A valid index is between 0 and arrayLenght-1.
Or more general:
If your input is wrong your programm blows up. You have to ensure that no value beyond an arrays capacity is accessed, this should be done in the line/loop in which it is accessed, not somewhere else.
In this case you have to ensure that results capacity is atleast blocklength+1.