arrays - how to search an element from a file in c -

my code needs 3 things:

• read numbers file file1 array (dynamic)
• sort numbers
• search numbers input file2 in sorted array.

.

#include <stdio.h> #include <stdlib.h> #include <math.h> #include <string.h>  int main (int argc, char *argv[]) {      file *fp1 = fopen ("myfile1.txt", "r");     if (fp1 == null) {         printf ("cannot open file");         exit (0);     }     file *fp2 = fopen ("test1.txt", "w");     if (fp2 == null) {         puts ("not able open file");         exit (1);     }     int = 0, num, j, k;     int *b = null;     int *c;     int a;     int size = 32;      b = malloc (sizeof (int) * size);      while (fscanf (fp1, "%d", &num) == 1) {         if (i < size) {             b[i] = num;             fprintf (fp2, "%d\r\n", num);             i++;         }         else {             c = malloc (sizeof (int) * 2 * size);             memcpy (c, b, size * sizeof (int));             free (b);              b = &c[0];             b[i] = num;             i++;             size = size * 2;             i++;              (j = 0; j < size; ++j) {                 (k = j + 1; k < size; ++k) {                     if (b[j] < b[k]) {                         = &b[j];                         b[j] = b[k];                         b[k] = a;                     }                 }             }             printf ("after sorting");             (j = 0; j < size; ++j)                 printf ("%d\n", b[j]);         }     }     return 0;     fclose (fp1);  /* note code never reached */     fclose (fp2); } 

i complete first part of reading in numbers file. not able understand how sort these numbers.

i trying apply bubble sort, puts 0s in array. how implementation incorrect?

& address-of operator. pass pointer. need a = b[i], since a int.

now sort numbers descending, if want them ascending change < > in if (b[j] < b[k]).

also must always check whether malloc succeeded or not e.g.:

if (!b) {     fprintf(stderr,"b alloc error");     exit(-1); } 

also might want consider realloc.

in addition there built-in qsort in stdlib.h, gives better time o(n^2).

note: haven't tested file operations, since said work properly.