[Bug c++/96538] New: Integer overflow when there are multiple operands in addition operation.

[prateek_kd at yahoo dot co.in]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96538

            Bug ID: 96538
           Summary: Integer overflow when there are multiple operands in
                    addition operation.
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: prateek_kd at yahoo dot co.in
  Target Milestone: ---

I am trying to add int values present in the vector and store in long int type
variable. If I am using for  loop for calculating the sum of vector elements
program produces correct sum. However if If I perform direct addition(e.g sum=
arr[0]+arr[1]...=arr[n]), the results obtained is incorrect and seems that
overflow is occurring. Below is the code snippet for you reference:

Input:942381765 627450398 954173620 583762094 236817490


Code leading to overflow/error: 
#include<bits/stdc++.h>
using namespace std;

int main()
{
vector<int> arr(5);
for(int i=0;i<5;i++)
{
cin>>arr[i];
}
sort(arr.begin(),arr.end());
long int  sum = 0,min_sum=0,max_sum=0;
sum = arr[1]+arr[2]+arr[3]
min_sum = arr[0]+ sum; 
max_sum = arr[4]+ sum;
cout<<min_sum<<" "<<max_sum<<endl;

return 0;
}


Output :-1904555549 -1187199419

Code producing correct output:

#include<bits/stdc++.h>
using namespace std;

int main()
{
vector<int> arr(5);
for(int i=0;i<5;i++)
{
cin>>arr[i];
}
sort(arr.begin(),arr.end());
long int  sum = 0,min_sum=0,max_sum=0;
for(int j=0;j<5;j++)
{
sum = sum+ arr[j];//after for loop sum = arr[1]+arr[2]+arr[3]
}
min_sum = arr[0]+ sum; 
max_sum = arr[4]+ sum;
cout<<min_sum<<" "<<max_sum<<endl;

return 0;
}



Output(for same input as above):
3581402857 4298758987