How to search a file using an array as search term

Question

I'm trying to parse a csv file and search it to find values that match my randomly generated array.

I've tried a few methods but im getting lost, I need to access the entire file, search for these values and output the index column that it belongs to.

my code for my random array generator as well as my search csv function:

EDIT:

edited code to make reproducible, with added comments, hopefully this matches criteria (besides given csv file obviously).

reproducible example:

#include <fstream>
#include <iostream>
#include <string>
#include <random>

using namespace std;


//fills array of size 6 with random numbers between 1-50
void random_array(int arr[]){
 
    for(int i=0;i<6;i++)
    {
        int num = rand()%51;
        arr[i]=num;
    }

}

int main(){
    string line;
    fstream file;
    
    int size = 6;
    int numbers[size];
    int found;

    //gets random array from random_array func
    srand(time(NULL));
    random_array(numbers);

    //opens file to search
    file.open("CSV directory here");
    if(file.is_open())
    {
        //print random array values
        for(int i = 0; i < size; i++){
            cout << numbers[i]<< " ";}
            cout << endl;
        
        //get file contents and search if contents of array exist in file
        while(getline(file, line)){
            
           for(int i = 0; i < size; i++){
            found = line.find(std::to_string(numbers[i]));

           if(found != string::npos) {
               //print found numbers
               cout << found << " ";
           }
        }
      }
            
    }

    return 0;
}

CSV format:

,Date,1,2,3,4,5,6,7
0,Wed 03 January 2001,5,6,16,17,19,22,40
1,Sat 06 January 2001,6,16,23,34,35,40,37

my output:

array generated:

35 35 38 37 16 31

numbers found:

26 33 33 39 24 31 34 33 24 6 28 31 33 33 30 0 32 34 33 30 27 38 26 29 29 33 7 24 29 26 26 26 24 24 0 30 30 36 0 0 23 27 0 0 7 36 36 27 30 30 27 27 26 26 32 29 23 38 32 32 28 28 7 25 29 37 25 29 29 26 23 34 31 28 25 31 28 28 34 32 32 35 38 40 25 37 37 35 40 40 30 30 42 42 42 36 35 28 31 25 37 7 27 36 33 36 33 29 39 29 35 34 34 40 40 43 31

Not related, but `srand` should be called once, in `main`. and [you shouldn't use eof in a loop condition](https://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-i-e-while-stream-eof-cons). Other than that, what's your actual question / problem you're encountering? — ChrisMM, Apr 12 '22 at 11:54
whats wrong with the code? (apart from being incomplete, please read about [mcve] and try to provide one) — 463035818_is_not_an_ai, Apr 12 '22 at 11:57
Thanks for the tips, ive fixed both issues. I guess my question is am I doing this correctly? my output isn't correct so I wasn't sure if I was handling my array search incorrectly in my getline section. the output seems almost random and doesnt match the array values at all. — sdh1998, Apr 12 '22 at 11:58
@sdh1998 Side note: hard coding `6` is poor a dangerous practice. Use a constant at least. — Jabberwocky, Apr 12 '22 at 12:03
Just to note, `std::cout << found` is printing the _location_ that the value was found, not the numbers that were found. — ChrisMM, Apr 14 '22 at 12:28

score 1 · Accepted Answer · answered Apr 12 '22 at 12:01

I'd recommend looking at the find function in more detail. None of its overloads take in an integer, the nearest match (and one that would be used) takes in a char ... So it would not be looking for strings like "12" it would be looking for the character which has a value of 12.

You need to first convert the number(s) to a string. A simple modification would be:

for ( int i = 0; i < 6; i++ ) {
   if( (offset = line.find( std::to_string( numbers[i] ) ) ) != string::npos ) {
       //do something
   }
}

How to search a file using an array as search term

1 Answers1