Thread: how to store file of big size

file1:

Code:

12E3F
1E34F
34EF5
......

there are 20000000000000 Rows in file1.
Can I store the file into 20000000000000*5 array ?
if not , how to implement it ？

Originally Posted by quzah

By 'store', I assume you mean 'load into memory all at the same time', which leads me to ask: Why?

To answer your question: No, you can't make a true array that size. You'll run out of stack space. Your best shot is to dynamically allocate it with something like malloc. But again, you're probably out of luck unless you're on a 64 bit OS. 100000000000000 is too big to fit in a 32bit data type.


Quzah.

Code:

#include "stdlib.h"
#include "stdio.h"
#include "string.h"

int main(int argc,char *argv[])
{
    char **p = (char **) malloc ( 50*sizeof(char));
    FILE *fr = fopen("test.data","r");
    char a;
    int i = 0;
    int m = 0;
    int n = 0;
    while ( fscanf(fr, "%c", &a ) == 1 )
    {
            //char line[10];
            //fgets(line,10,fr);
            
            
            if ( a == '\n' )
            {
                 m = 0;
                 n++;
            } 
            else
            {
                *(*(p+n)+m) = a;
                m++;
            }
            
            
            
    }
            
            
    return 0;
}

this is my test program . why error ?

Originally Posted by quzah

Why are you using a pointer to a pointer? If you want to pretend it's a 2D array, then you need two steps:

Code:

char **p;
    p = malloc( sizeof( char * ) * numberofrows );
    for( x = 0; x < numberofrows; x++ )
        p[ x ] = malloc( numberofcolumnsperrow );

You are using fscanf to read a single character. That's not its best suit. Why not just use fgetc if you only want one character?

But to answer your question: it's crashing because you're not allocating memory right. See point one again.

Edit: And to go along with what Elysia said, stop making new threads for the same exact topic. You have like four now.


Quzah.

Your answer is appreciated, Thanks

Originally Posted by quzah

Why are you using a pointer to a pointer? If you want to pretend it's a 2D array, then you need two steps:

Code:

char **p;
    p = malloc( sizeof( char * ) * numberofrows );
    for( x = 0; x < numberofrows; x++ )
        p[ x ] = malloc( numberofcolumnsperrow );

You are using fscanf to read a single character. That's not its best suit. Why not just use fgetc if you only want one character?

But to answer your question: it's crashing because you're not allocating memory right. See point one again.

Edit: And to go along with what Elysia said, stop making new threads for the same exact topic. You have like four now.


Quzah.

your suggestion is appreciated