/* BEGIN file_mul.c */
/*
From news:comp.lang.c
> I want to read integers from a text file and
> want to do some operation in the main program.
> To be more specific I need to multiply each of these integers 
> with another set of integers stored in an array.
*/
#include "file_lib.h"
#include "list_lib.h"

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

#define INTEGERS        17
#define LU_RAND_SEED    123456789LU
#define LU_RAND(S)      ((S) * 69069LU + 362437 & 0XFFFFFFFF)
#define NMEMB(A)        (sizeof (A) / sizeof *(A))

int main(void) 
{
    int rc;
    size_t index;
    FILE *fp;   
    char fn[L_tmpnam];
    long unsigned array[INTEGERS];
    long unsigned seed = LU_RAND_SEED;
    size_t size = 0;
    char *buff = NULL;
    list_type *head = NULL;
    list_type *tail = NULL;

    puts("/* BEGIN file_mul.c output */\n");
    tmpnam(fn);
    fp = fopen(fn, "w"); 
    if (fp == NULL) {
        fputs("fopen(fn), \"w\") == NULL\n", stderr);
        exit(EXIT_FAILURE);
    }
    puts("File open for writing.");
    puts("File values:");
    for (index = 0; index != NMEMB(array); ++index) {
        seed = LU_RAND(seed);
        fprintf(    fp, "%lu\n", seed & 0xff);
        fprintf(stdout, "%4lu" , seed & 0xff);
        seed = LU_RAND(seed);
        array[index] = seed & 0x3;
    }
    putchar('\n');
    fclose(fp);
    puts("File closed.");
    puts("Array values:");
    for (index = 0; index != NMEMB(array); ++index) {
        fprintf(stdout, "%4lu", array[index]);
    }
    putchar('\n');
    fp = fopen(fn, "r"); 
    if (fp == NULL) {
        fputs("fopen(fn, \"r\") == NULL\n", stderr);
        exit(EXIT_FAILURE);
    }
    puts("File open for reading.");
    puts("Reading file into a linked list...");
    while ((rc = get_line(&buff, &size, fp)) > 0) {
        tail = list_append(&head, tail, buff, rc);
        if (tail == NULL) {
            fputs("tail == NULL\n", stderr);
            break;
        }
    }   
    fclose(fp);
    puts("File closed.");
    fp = fopen(fn, "w"); 
    if (fp == NULL) {
        fputs("fopen(fn), \"w\") == NULL\n", stderr);
        exit(EXIT_FAILURE);
    }
    puts("File open for writing.");
    puts("Writing file with products of list and array values...");
    tail = head;
    index = 0;
    while (index != NMEMB(array) && tail != NULL) {
        seed = strtoul(tail -> data, NULL, 10);
        tail = tail -> next;
        fprintf(fp, "%lu\n", array[index] * seed);
        ++index;
    }
    list_free(head, free);
    puts("List is freed.");
    fclose(fp);
    puts("File closed.");
    fp = fopen(fn, "r"); 
    if (fp == NULL) {
        fputs("fopen(fn, \"r\") == NULL\n", stderr);
        exit(EXIT_FAILURE);
    }
    puts("File open for reading.");
    puts("File values:");
    while ((rc = get_line(&buff, &size, fp)) > 0) {
        fprintf(stdout, "%4s", buff);
    }   
    putchar('\n');
    free(buff);
    puts("Line reading buffer is freed.");
    fclose(fp);
    puts("File closed.");
    remove(fn);
    puts("File removed.");
    puts("\n/* END file_mul.c output */");
    return 0;
}

/* END file_mul.c */