How to clear blank lines in files using c?

Question

I am working on a management system project and want to clear the file before adding data to it. I am using this code as a reference. I have rewritten the code from the reference and instead of writing the data from the temporary file(tmp) back to the original(FILE_NAME), I have printed it out to the terminal.

When I compile and run the program, it prints all the content and a few more lines after the end of the file. After this it stops and doesn't finish execution. I have added to comments to help understand my thought process better.

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

#define BUFFER_SIZE 1000
#define FILE_NAME "data.csv"

int main()
{
    FILE* file;
    char buffer[BUFFER_SIZE];

    // Opening file
    if(file = fopen(FILE_NAME, "r+"))
    {
        char c; // To get character from buffer
        int i = 0; // Index for the buffer character
        int isEmpty = 1; // If the line is empty

        FILE* tmp;
        if(tmp = tmpfile())
        {
            while(1)
            {
                buffer[i++] = c;
            
                if(c != '
') // Checking for blank lines
                {
                    isEmpty = 0;
                }
                else
                {
                    if(c == '
' && isEmpty == 0) // Read a word; Print to tmp file
                    {
                        buffer[i] = '';
                        fprintf(tmp, "%s", buffer);
                        i = 0;
                        isEmpty = 1;
                    }
                    else if(c == '
' && isEmpty == 1) // NOT SURE WHY THIS IS IMPORTANT
                    {
                        buffer[i] = '';
                        i = 0;
                        isEmpty = 1;
                    }
                }
            
                if(c == EOF)
                { break; }

                while(1) // Loop to print contents of tmp file onto terminal
                {
                    c = getc(tmp);

                    printf("c: %c", c);

                    if(c == EOF)
                    { break; }
                }
            }   
        }
        else
        {
            printf("Unable to open temporary file
");
        }

        fclose(file);
    }
    else
    {
        printf("Unable to open file.");
    }

    getchar();
    return 0;
}

UPDATE: I've modified a few lines and have got it working.

1. I'd forgotten to assign c in the above program. Also @Barmar won't char c work just as well as int c. Characters can be integers as well right?

2. Why would large indentations lead to bugs? I find the blocks of code to be more differetiated.

#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#define BUFFER_SIZE 1000
#define FILE_NAME "data.csv"

int main()
{
    // Variable Declaration
    FILE* file;
    char buffer[BUFFER_SIZE];

    // Opening file 
    if( file = fopen(FILE_NAME, "r+") )
    {
        char c; // Reading characters from the file
        int i; // Index of the characters
        int isEmpty = 1; // 1-> character is empty; 0-> character is not empty

        FILE* tmp;
        if( tmp = fopen("tmp.csv", "a+") )
        {   
            char c; // Reading characters from files 
            int i = 0; // Index
            int isEmpty = 1; // 1->previous word is empty; 0->previous word is not empty
            while( (c = getc(file)) != EOF)
            {

                if( c != '
' && c != ' ' && c != '' && c != ',')
                {
                    isEmpty = 0;
                    buffer[i++] = c;
                }
                else
                {
                    if( c == '
' && isEmpty == 0 )
                    {
                        buffer[i] = '';
                        fprintf(tmp, "%s", buffer); 
                        i = 0;
                        isEmpty = 1;
                    }
                    else if( c == '
' && isEmpty == 1 )
                    {
                        buffer[i] = '';
                        i = 0;
                    }
                }
            }

            fclose(tmp);    
        }
        else
        {
            printf("Unable to open temporary file
");
        }

        fclose(file);
    }
    else
    {
        printf("Unable to open file
");
    }

    return 0;
}

Are there are ways to simplify the program and make it more compact or less error prone?

question from:https://stackoverflow.com/questions/66050201/how-to-clear-blank-lines-in-files-using-c

Answer 1

Waitting for answers