how to read a file in in c 2b 2b

1// io/read-file-sum.cpp - Read integers from file and print sum.
2// Fred Swartz 2003-08-20
3
4#include <iostream>
5#include <iomanip>
6#include <fstream>
7using namespace std;
8
9int main() {
10    int sum = 0;
11    int x;
12    ifstream inFile;
13    
14    inFile.open("test.txt");
15    if (!inFile) {
16        cout << "Unable to open file";
17        exit(1); // terminate with error
18    }
19    
20    while (inFile >> x) {
21        sum = sum + x;
22    }
23    
24    inFile.close();
25    cout << "Sum = " << sum << endl; 
26    return 0;
27}
28