BinarySearch function not working - c++

Question

I've got a menu that I've been working on, and everything now seems to work, except for the binary search function. I am entering the size of the array, filling the array, printing it, then sorting it with my chronological menu, and then when I do sequential search, it seems to work. However, binary search does not even return -1 to indicate that the number was not found, the program just stops. Suggestions? Thanks.
#include<iostream>
#include <cmath>
#include <cstdlib>
using namespace std;
int size=0; //global variable size
int a[100]; //global array
int getSize()
{
cout << "Array Size: ";
cin >> size;
return size;
cout << endl;
}
int sequentialSearch(int n)
{
for(int i=0;i<size;i++)
{
if(n==a[i])
{
return (i+1);
}
}
return -1;
}
int binarySearch(int n)
{
int low=0,high=size,mid;
while(low<=high)
{
mid=(low+high)/2;
if(a[mid]==n)
{
return mid+1;
}
else if(a[mid]>n)
high=mid-1;
else if(a[mid]<n)
low=mid-1;
}
return -1;
}
void sort1()
{
int i, j;
for (i = 0; i < size-1; i++)
{
for (j = 0; j < size-i-1; j++)
if (a[j] > a[j+1])
{
int temp=a[j];
a[j]=a[j+1];
a[j+1]=temp;
}
}
}
void sort2()
{
int i, j, m;
for (i = 0; i < size-1; i++)
{
m = i;
for (j = i+1; j < size; j++)
{
if (a[j] > a[m])
m = j;
}
int temp=a[m];
a[m]=a[i];
a[i]=temp;
}
}
void printMenu()
{
cout<<"0. Exit\n";
cout<<"1.Get the size needed for todays use of the array \n";
cout<<"2.Fill an array with random numbers from 1-100 \n";
cout<<"3.Print the array with position numbers \n";
cout<<"4.Sort the array in ascending sequence \n";
cout<<"5.Sort the array in descending sequence \n";
cout<<"6.Sequential search of the array for a target\n";
cout<<"7.Binary search of the array for a target\n";
}
void printTheArray()
{
for(int i=0;i<size;i++)
{
cout<<a[i]<<" is at position :"<<i+1<<endl;
}
}
void fillWithRandom()
{
for(int i=0;i<size;i++)
{
int x=rand()%101;
a[i]=x;
}
}
void dispatch(int ch)
{
switch(ch)
{
case 1:cout<<"Size of array :"<<getSize() << endl;
break;
case 2:fillWithRandom();
break;
case 3: printTheArray();
break;
case 4:sort1();
break;
case 5:sort2();
break;
case 6:
{
cout<<"Enter the number you want to search\n";
int t;
cin>>t;
int res1=sequentialSearch(t);
if(res1!=-1)
cout<<"Found in position :"<<res1<<endl;
else if(res1==-1)
cout<<"Not Found \n";
break;
}
case 7:
{
cout<<"Enter the number you want to search\n";
int t;
cin>>t;
int res=binarySearch(t);
if(res!=-1)
cout<<"Found in position :"<<res<<endl;
else if(res==-1)
cout<<"Not Found \n";
break;
}
default:cout<<"wrong choice\n";
}
}
int main ()
{
printMenu();
int choice;
cout<<"Type in a choice"<<endl;
cin>>choice;
while(choice!=0)
{
dispatch(choice); // one big switch statement
printMenu();
cout<<"Type in a choice"<<endl;
cin>>choice;
}
cout << endl;
// wrap-up
cout << "This program is coded by Troy Wilms" << endl; // fill in your name
// stops the program to view the output until you type any character
return 0;
}

Answer 1

for example, if you try finding 4 in list {1, 3, 5}, low will be always 0 and high will be always 2. because of the code 'low = mid - 1' I think it should be changed to 'low = mid + 1'