bnr script

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


/*--- structure that defines a node ---*/

struct Node{
    char data;
    struct Node *next;
    struct Node *previous;
};
typedef struct Node NODE;

/*--- Function Prototypes ---*/

void ReadFromFile(NODE**, char*);
static void WriteInt(char*, int);
static void WriteChar(char*, char);
extern NODE* MakeNode(char);
extern void InsertEnd(NODE**, char);
static char Decode(NODE**, int);
static int Code(NODE**, char);
static int ListLength(NODE*);

int main(int argc, char **argv){
    if(argc <= 4){
        printf("Invalid number of parameters");
        fprintf(stderr, "Error: %d: %s\n", errno, strerror(errno));
    }
    NODE *TopNode = NULL;

    fclose(fopen(argv[2], "w"));
    int i;
    printf("Parameter listing: \n");
    for(i = 1; i <argc; i++){
        printf("  %i: %s\n", i, argv[i]);
    }
    ReadFromFile(&TopNode, argv[1]);
    if(*argv[3] == 'D'){
        int i;
        char c;
        for(i = 4; i < argc; i++){
            c = Decode(&TopNode, atoi(argv[i]));
            WriteChar(argv[2], c);
        }
    }
    if(*argv[3] == 'C'){
        char* StrCode = argv[4];
        int i;
        int PositiveTurn;
        int NegativeTurn;
        for(i = 0; i < strlen(StrCode); i++){
            PositiveTurn = Code(&TopNode, StrCode[i]);
            NegativeTurn = PositiveTurn - ListLength(TopNode);
            if(PositiveTurn <= abs(NegativeTurn)){
                printf("%i\n", PositiveTurn);
                WriteInt(argv[2], PositiveTurn);
            }
            else{
                printf("%i\n", NegativeTurn);
                WriteInt(argv[2], NegativeTurn);
            }
        }
    }
}

/*--- Opens the file and reads the values
Inputs: Double pointer of TopNode and text file reference
Outputs: Void ---*/

void ReadFromFile(NODE **TopNode, char *FileName){
    FILE *fp;
    char ch;
    fp = fopen(FileName, "r");

    if (fp == NULL){
        printf("Cannot open file for read access\n");
        fprintf(stderr, "Error: %d: %s\n", errno, strerror(errno));
        exit(1);
    }

    printf("\nCoding wheel values:\n  ");
    while (!feof(fp)){
        ch = fgetc(fp);
        if (ch != 10 && ch != -1){
            printf("%c", ch);
            InsertEnd(TopNode, ch);
        }
    }
    printf("\n\n");
    fclose(fp);
}


/*---Writes Integer values into a text file
Inputs: Pointer of a file name, integer value
Outputs: Void ---*/

static void WriteInt(char *FileName, int num){
    FILE *fp;
    char ch;
    fp = fopen(FileName, "a");

    if (fp == NULL){
        printf("Cannot open file for write access\n");
        fprintf(stderr, "Error: %d: %s\n", errno, strerror(errno));
        exit(1);
    }
    fprintf(fp, "%i\n", num);

}

static void WriteChar(char *FileName, char data){
    FILE *fp;
    char ch;
    fp = fopen(FileName, "a");

    if (fp == NULL){
        printf("Cannot open file for write access\n");
        fprintf(stderr, "Error: %d: %s\n", errno, strerror(errno));
        exit(1);
    }
    fprintf(fp, "%c", data);

}

/*---Writes character values into a text file
Inputs: Pointer of a file name, character value
Outputs: Void ---*/

extern NODE* MakeNode(char data){
    NODE * NewNode = malloc(sizeof(*NewNode));
    if (NewNode != NULL){
        NewNode -> data = data;
        NewNode -> next = NULL;
        NewNode -> previous = NULL;
    }
    return NewNode;
}

/*---Creates the doubly linked list
Inputs: Double pointer of TopNode, character value
Outputs: Void ---*/

extern void InsertEnd(NODE **TopNode, char data){
    if (*TopNode == NULL){
        NODE *NewNode = MakeNode(data);
        NewNode -> data = data;
        NewNode -> next = NewNode -> previous = NewNode;
        *TopNode = NewNode;
        return;
    }

    NODE *LastNode = (*TopNode) -> previous;
    NODE *NewNode = MakeNode(data);
    NewNode -> data = data;
    NewNode -> next = *TopNode;
    (*TopNode) -> previous = NewNode;
    NewNode -> previous = LastNode;
    LastNode -> next = NewNode;
}

/*---Decodes the given text
Inputs: Double pointer of TopNode, integer value
Outputs: a character value ---*/

static char Decode(NODE **TopNode, int num){
    int n;
    NODE* NewNode = *TopNode;
    if (num >= 0){
        for(n = 0; n < num; n++){
            NewNode = NewNode -> next;
        }
        printf("%c\n", NewNode -> data);
    }
    else{
        for(n = 0; n > num; n--){
            NewNode = NewNode -> previous;
        }
        printf("%c\n", NewNode -> data);
    }
    *TopNode = NewNode;
    return NewNode -> data;
}

/*---Codes the given text
Inputs: Double pointer of TopNode, character value
Outputs: an Integer value ---*/

static int Code(NODE **TopNode, char data){
    int n = 0;
    NODE* NewNode = *TopNode;
    while(NewNode -> next != *TopNode){
        if(NewNode -> data != data){
            NewNode = NewNode -> next;
            n++;
        }
        else{
            break;
        }
    }
    *TopNode = NewNode;
    return n;
}

/*---Finds the length of the list
Inputs: Pointer of TopNode
Outputs: an Integer value ---*/

static int ListLength(NODE *TopNode){
    int n = 1;
    NODE* NewNode = TopNode;
    while(NewNode -> next != TopNode){
        NewNode = NewNode -> next;
        n++;
    }
    return n;
}