Question

I get SIGABORT when running this code.
I discovered that I am suppose to use square brackets but why the behavior is same.

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    double * dp  = new double (5); // what do round brackets mean, and why the behvior

    std::ifstream fid("testdata.txt");
    fid >> dp[0] >> dp[1] >> dp[2] >> dp[3] >> dp[4];
    fid.close();
}

Content of “testdata.txt” is:

4.0 5. 6. 6. 8. 7. 952.

This error happens only when there is 5 or more doubles in file.

Answer 1

Change

new double(5);

to

new double[5];

The first syntax creates one double on the heap and sets it to 5. The second syntax creates an array of five doubles.

Either way, it is a good practice to delete dp when you’re done with it. In the first case, the correct syntax is delete dp; and in the second, delete[] dp;.