How to make Interactive program in BST ? C Lang - c

Question

I need to to open and read multiple text files which will be stored similar to binary search tree construction.
NOTE: They all need to be opened and their content stored before user enters his input.
I really do need some advice, because I do not see my errors any more.
However, what I really don't get, is how to make it interactive ?
When I press 'A', it needs to read text from the left node and opposite.
Structure of output:
------------------\n
\n
Title\n
file1 // file present - 'A'
file2 // file empty/not empty - 'B'\n
Text\n
\n
Your choice (A/B):\n
This is how the programs output should look at the beginning:
terminal
Elements of struct
typedef struct _Elements_
{
char* title_;
struct _Elements_* left;
struct _Elements_* right;
char* text_;
} Elements;
//Forward initialization is present
int main (int argc, char* argv[])
{
char returned_value;
Elements element;
if (argc != 2)
{
printf("Usage: ./ass2 [file-name]\n");
return 1;
}
returned_value = openFile(&element, argv[1]);
while(returned_value != ('A' || 'B'))
{
repeatEntry(returned_value); // Function to scan the value
}
// Tricky part! Read from left ???
if(returned_value == 'A')
{
printf("%s",element.left->text_);
}
else
{
printf("%s",element.right->text_);
}
return 0;
}
//Here i wanna initialize node elements
// For every malloc, I have to make sure that it succeeded
Elements* newNode(Elements* element)
{
Elements* newNode = (Elements*)malloc(sizeof(Elements));
if(newNode == NULL)
{
printf("[ERR] Out of memory.\n");
return (void*)2; // void* - to avoid warning of different type?
}
newNode->title_ = NULL;
newNode->left = NULL;
newNode->right = NULL;
newNode->text_ = NULL;
return newNode;
}
//Function that opens the files
char openFile(Elements* element, char* input)
{
// Create new memory if tree is empty
if(element == NULL)
{
return newNode(element);
}
FILE* file_open = fopen(input, "r");
if (file_open == NULL)
{
printf("[ERR] Could not read file %s.\n", input);
return 3;
}
// Local variables to handle the parsing file ?
char line[80];
int lenght_of_the_line; // Was just for me
int line_number = 0; // this also
// Do i really need local variables beside struct ?
char* title_local = NULL;
char* first_file = NULL;
char* second_file = NULL;
char* text_local = NULL;
while(fgets(line, 80, file_open))
{
lenght_of_the_line = strlen(line);
//printf("%d ", lenght_of_the_line);
//printf("%s ", line);
// Get title
if((line[lenght_of_the_line - 1] == '\n') && (line_number == 0))
{
title_local = (char*)malloc(lenght_of_the_line * (sizeof(char)) + 1);
if(title_local == NULL)
{
printf("[ERR] Out of memory.\n");
return 2;
}
strcpy(title_local, line);
printf("%s ", element->title_ = title_local);
printf("\n");
}
// Get 1st file name
else if( (line[lenght_of_the_line - 1] == '\n') && (line_number == 1) )
{
if( (line[lenght_of_the_line - 5] == '.') &&
(line[lenght_of_the_line - 4] == 't') &&
(line[lenght_of_the_line - 3] == 'x') &&
(line[lenght_of_the_line - 2] == 't') )
{
// Allocate enough memory for first file name
first_file = (char*)malloc(lenght_of_the_line * (sizeof(char)) + 1);
if(first_file == NULL)
{
printf("[ERR] Out of memory.\n");
return 2;
}
strcpy(first_file, line);
//name of file to open and store to left node
//Seems to work, since I got no error
openFile(element->left, first_file);
}
}
// Get 2nd file name
else if( (line[lenght_of_the_line - 1] == '\n') && (line_number == 2) )
{
if( (line[lenght_of_the_line - 5] == '.') &&
(line[lenght_of_the_line - 4] == 't') &&
(line[lenght_of_the_line - 3] == 'x') &&
(line[lenght_of_the_line - 2] == 't') )
{
second_file = (char*)malloc(lenght_of_the_line * (sizeof(char)) + 1);
if(second_file == NULL)
{
printf("[ERR] Out of memory.\n");
return 2;
}
strcpy(second_file, line);
openFile(element->right, second_file);
}
}
else
{
text_local = (char*)malloc(lenght_of_the_line * (sizeof(char)) + 1);
if(text_local == NULL)
{
printf("[ERR] Out of memory.\n");
return 2;
}
strcpy(text_local, line);
element->text_ = text_local;
printf("%s", element->text_);
}
// Increase line number for 1
line_number++;
}
//free(line);
fclose(file_open);
printf("\n");
printf("Your choice (A/B)? ");
char user_input;
scanf("%c", &user_input);
// DONT FORGET TO FREE THE MEMORY !
return user_input;
}

Answer 1

This
while(returned_value != ('A' || 'B'))
does not do what you probably expect. It compares the returned value to whatever value your compiler uses to represent true.
Currently your loop is hence likely to seem an endless loop, while waiting for returned_value to be identical to true.
You need
while((returned_value != 'A') && (returned_value != 'B'))
This will leave the loop when returned_value is identical to either 'A' or 'B'.
That way the endless loop problem is solved, which is likely the core problem preventing your file BST from being interactive.
By the way, for users convenience I recommend to also accept 'a' or 'b'.
For avoiding a "try again" after each input, use
scanf(" %c", &user_input);
with a space at the start, for ignoring leading white space, including the newline/return after each entered 'A' or 'B'.