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binary search giving errors

dannyboy77 (3)
binarysearch not working
My errors are:

lab#7.cc:139:3: error: stray ‘\342’ in program
int last = numElems − 1;
^
lab#7.cc:139:3: error: stray ‘\210’ in program
lab#7.cc:139:3: error: stray ‘\222’ in program
lab#7.cc:141:3: error: stray ‘\342’ in program
int position = −1;
^
lab#7.cc:141:3: error: stray ‘\210’ in program
lab#7.cc:141:3: error: stray ‘\222’ in program
lab#7.cc:153:13: error: stray ‘\342’ in program
last = middle − 1;
^
lab#7.cc:153:13: error: stray ‘\210’ in program
lab#7.cc:153:13: error: stray ‘\222’ in program
lab#7.cc: In function ‘int binarySearch(std::string*, int, std::string)’:
lab#7.cc:139:27: error: expected ‘,’ or ‘;’ before numeric constant
int last = numElems − 1;
^
lab#7.cc:153:31: error: expected ‘;’ before numeric constant
last = middle − 1; 

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  #include <iostream>
#include <iomanip>
#include <string>
using namespace std;


void calcdata(int [], float [] , char [], string []);

void selectionSort(string [], char [], float []);

int binarySearch( string [], int, string); 

void displayName(string[] , char [], int); 
   
int main ()
{
	
int grade [5]= { 0 }; 
float avg [4] = { 0 }; //# of tests
char calif[5]={0};
int sum=0;
	
string name[5];
char again;


for (int j=0; j<5; j++){
	cout<<"Enter name of student " <<j+1 <<": " <<"\n";
	cin >> name[j];
	cout<<": " <<j+1 <<"Enter students scores \n";
	
	for (int i=0;i<4; i++){
	cout<<"The grade " << i+1 << "es : " << "\n";
	cin >>grade[i] ;
	
	sum=sum + grade[i];
 avg[j]=sum/4;
 }
			
	sum=0;
}
	

   	calcdata(grade,avg,calif,name);
   	
   //orginize calcdata
    selectionSort(name, calif, avg); 
 
 do{   
 string studName;  // To hold students name 
 int index;  // To hold search results 
  
    
    cout<<"What name do you want?\n";
    cin>>studName;
     // Search for the name. 
            index = binarySearch(name,5, studName);
            
            while(index == -1){
             cout << "Error: Este nombre no esta en la base de datos. Re-entre: ";
             cin >> studName;
             index = binarySearch(name,5, studName);
            }
            
            displayName(name, calif, index); 
   
            // Does the user want to do this again? 
            cout << "Would you like to look up another name? (y/n) "; 
            cin >> again; 
        } while (again == 'y' || again == 'Y'); 
 
        return 0; 
 } 
  
  



void calcdata(int grade[], float avg[], char calif[], string name[])
{

for (int j=0;j<5; j++) {
	if(avg[j]<=100 && avg[j]>=90)
	calif[j]='A';
	else
		if(avg[j]<=89 && avg[j]>=80)
		calif[j]='B';
		else
			if(avg[j]<=79 && avg[j]>=70)
			calif[j]='C';
			else
				if(avg[j]<=69 && avg[j]>=60)
				calif[j]='D';
				else
				calif[j]='F';}

for(int j=0;j<5;j++){
cout << "Name: " << name[j]
      <<" Average: " << avg[j]
       <<" Grade: " << calif[j]
       << endl;
    
}

}

 void selectionSort(char calif[], string name[], float avg[]) 
{
 
for (int startIndex = 0; startIndex < 5; ++startIndex)
{

int smallestIndex = startIndex;


for (int currentIndex = startIndex + 1; currentIndex < 5; ++currentIndex)
{

if (name[currentIndex] < name[smallestIndex])
	smallestIndex = currentIndex;
}


std::swap(name[startIndex], name[smallestIndex]);
std::swap(calif[startIndex], calif[smallestIndex]);
std::swap(avg[startIndex],avg[smallestIndex]);
}

  }
  

     


 int binarySearch(string array[], int numElems, string value)
 {
    
  int first = 0;   
  int last = numElems − 1;      
  int middle;
  int position = −1;     
  bool found = false;
  
  while (!found && first <= last){         
    middle = (first + last) / 2;     
    if (array[middle] == value)  
    { 
           found = true; 
           position = middle; 
    } 
    else 
       if (array[middle] > value)  
            last = middle − 1; 
       else 
           first = middle + 1;   
    }
    return position;
}  


 void displayName( string name[],  char calif[], int index)  
   { 
       cout << "Name: " << name[index] << endl; 
       cout << "Grade: " << calif[index] << endl; 
       
   }
closed account (LA48b7Xj)
Try retyping the (-) minus.
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