CODEWITHSUNDEEP
c++stl
toto
toto

Reputation: 900

How do I use CIN to read values from a file (64 bit integer)

Let's say I have the file input.txt containing the following numbers :

2 1 1 888450282
1 2

I need to read the first line in separate variables (a,b,c,d). The big value can be big like a 64 bit integer. How do I use C++ IO to do this? And the second line can have 1 to N values.

Normally I do this in C but I want to learn the C++ library and I'm also not very confortable with 64 bit integers in C++.

Upvotes: 2

Views: 6505

Answers (2)

KyleWpppd
KyleWpppd

Reputation: 2030

If you are only concerned about the first line of the file you can use something like the following to get it. 

#include <fstream>
#include <iostream>

And the following code will handle the file. 

    ifstream file("yourfile.txt", ios::in);
    int a, b, c;
    long long d;
    file >> a >> b >> c >> d;
    printf("a: %d, b: %d, c: %d, d: %lld", a, b, c, d);

    file.close();

Upvotes: 1

kennytm
kennytm

Reputation: 523344

You use iostream in the usual way, i.e. read it into a 64-bit-sized integer:

 #include <stdint.h>

 uint64_t value;
 std::cin >> value;

BTW, you could also use stdio in the form

 #include <inttypes.h>
 #include <stdint.h>

 uint64_t value;
 fscanf(file, "%"PRiu64"", &value);

Upvotes: 2

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