Counting the input numbers from a text file in C++

Question

How do I count the input integers/numbers from a text file that is separated by spaces. I need to know how many numbers does the user inputted via file not from the console.

Here is what I did. But it counts all the numbers instead.

// Counting of Arrival Time //

ifstream arrival_counting;
arrival_counting.open("arrival.in");
if (arrival_counting.fail()) {
    cout << "Input file opening failed.\n" << endl;
    exit(1);
}

int count_arr = 0;
char next1;
arrival_counting.get(next1);
while(!arrival_counting.eof()) {
    if(isdigit(next1)) {
        count_arr++;
    }
    arrival_counting.get(next1);
}

// Counting of Service time //

ifstream service_counting;
service_counting.open("service.in");
if (service_counting.fail()) {
    cout << "Input file opening failed.\n" << endl;
    exit(1);
}

int count_ser = 0;
char next2;
service_counting.get(next2);
while(!service_counting.eof()) {
    if(isdigit(next2)) {
        count_ser++;
    }
    service_counting.get(next2);
}

cout << "ARRIVAL: " << count_arr << endl;
cout << "SERVICE: " << count_ser << endl;
arrival_counting.close();
service_counting.close();

arrival.in

12 31 63 95 99 154 198 221 304 346 411 455 537

service.in

40 32 55 48 18 50 47 18 28 54 40 72 12

See http://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-considered-wrong please. — πάντα ῥεῖ, Nov 15 '16 at 17:57

score 2 · Answer 1 · answered Nov 15 '16 at 17:48

2

ifstream arrival_counting("arrival.in");
if (arrival_counting.fail()) {
    cout << "Input file opening failed.\n" << endl;
    exit(1);
}

int count_arr = 0;
int next1;
while(arrival_counting >> next1) {
    count_arr++;
}

answered Nov 15 '16 at 17:48

timrau

21,494
4
47
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Vlad from Moscow · Accepted Answer · 2016-11-15T18:07:59.830

1

You can count the numbers that are present in a file in one line.

Here you are.

#include <iterator>

//..

std::ifstream arrival_counting("arrival.in");

if (arrival_counting.fail()) {
    std::cout << "Input file opening failed.\n" << std::endl;
    exit(1);
}

auto n = std::distance( std::istream_iterator<int>( arrival_counting ),
                        std::istream_iterator<int>() );

edited Nov 15 '16 at 18:07

answered Nov 15 '16 at 17:49

Vlad from Moscow

224,104
15
141
268

Where is defined count with two arguments? I can't see the reference – amchacon Nov 15 '16 at 17:57
@amchacon I am sorry. I have not yet written the reference.:) – Vlad from Moscow Nov 15 '16 at 18:10
@VladfromMoscow thank you so much! It really helped me :) – Maya Nov 15 '16 at 18:32
@Mayz I hope.:) – Vlad from Moscow Nov 15 '16 at 18:37
@amchacon I am in two forums simultaneously: in SO and ruSO. So sometimes I am absentminded.:) – Vlad from Moscow Nov 15 '16 at 19:20

Counting the input numbers from a text file in C++

2 Answers2