Thread: programme, prime factorisation

Hey! I'm a complete beginner and I want to write a programme which does the prime factorisation of numbers. The numbers are in a file. The prime factorization should be in a new file. I have written everything and the programme successfully debugged but the window opened and closed. I don't know what's wrong with it.

This is a part of my code

Code:

{
                      int number_ofnumbers=0;
                      char c;
                      fscanf(f,"%c", &c);
                      if (c=='\0')
                      number_ofnumbers++;

                      int a[number_ofnumbers];
                      int i;
                      for (i=0; i<number_ofnumbers; i++)
                      {
                          int j;
                          int k=0;


                          int b[100];

                          if (a[i]>1)
                          {
                              for(j=2; j<=sqrt(a[i]); j++)
                                while ((a[i]% j) == 0)
                                  {
                                     if (sqrt(a[i]) != j)
                                     {
                                         k++;
                                         b[k] = a[i];
                                     }
                                     else
                                     {
                                      k++;
                                      b[k] = j;

                                     }
                                  }

Could anyone look whether it's ok or not? I'd be very thankful.

well hard to duplicate what is going on, if you dont post the entire code so we can run it, kinda common sense there.....

Here's the whole code:

Code:

#include <math.h>
#include <stdlib.h>
#include <stdio.h>



int main()
{
    FILE *f; 
    f = fopen("we.txt","r"); 

    if (f) {
            printf ("\The file connot be opened.\n");
            return -1;
            }
    while (!feof(f)) {
                      int number_ofnumbers=0;
                      char c;
                      fscanf(f,"%c", &c);
                      if (c=='\0')
                      number_ofnumbers++;

                      int a[number_ofnumbers];
                      int i;
                      for (i=0; i<number_ofnumbers; i++)
                      {
                          int j;
                          int k=0;


                          int b[100];

                          if (a[i]>1)
                          {
                              for(j=2; j<=sqrt(a[i]); j++)
                                while ((a[i]% j) == 0)
                                  {
                                     if (sqrt(a[i]) != j)
                                     {
                                         k++;
                                         b[k] = a[i];
                                     }
                                     else
                                     {
                                      k++;
                                      b[k] = j;

                                     }
                                  }

     FILE *f2;
     int z;
    f2 = fopen("output.txt", "r");
    for(z = 0; z < k; z++){
    fputs("b[z]",f2);
    }
                          }
                       }
    }

    fclose (f);
    return 0;
}

I open a file with numbers. Then I count how many numbers there are in the file. Then goes the prime factorisation. The programme should show the prime factorisation in the 'output' file.

I changed it but now I get 3 errors and 1 warning.

Code:

 
#include <math.h>
#include <stdlib.h>
#include <stdio.h>



int main()
{
    FILE *f;
    f = fopen("input.txt","r");

    if (!f) {
            printf ("\The file connot be opened.\n");
            return -1;
            }
    while (feof(f)==0) {
                      int number_ofnumbers=0;
                      char c;
                      fscanf(f,"%c", &c);
                      if (c=='\0')
                      number_ofnumbers++;

                      int a[number_ofnumbers];
                      int i;
                      for (i=0; i<number_ofnumbers; i++)
                      {
                          int j;
                          int k=0;


                          int b[100];

                          if (a[i]>1)
                          {
                              for(j=2; j<=sqrt(a[i]); j++)
                                while ((a[i]% j) == 0)
                                  {
                                     if (sqrt(a[i]) != j)
                                     {
                                         k++;
                                         b[k] = a[i];
                                     }
                                     else
                                     {
                                      k++;
                                      b[k] = j;

                                     }
                                  }
    fclose (f);

    FILE *f2;
    int z;
    f2 = fopen("output.txt", "r");
    for(z = 0; z < k; z++){
    fputs("b[z]",f2);
    }
                          }
                       }
    }

    fclose (f2);
    return 0;
}

What do you mean by the actual element of b[z]? I want the output file to show all elements of b[z].

Could you explain in your own words why feof is bad for loop controlling?

I want to know how many numbers there are in the file by adding spaces.