so for one of my classes, I have to create a .txt file in c and then delete a few lines off of it. I wrote a separate function for each of these operations.

the creation function goes smoothly either way but the delete function only works after I separately create the file AND THEN delete while the the creation function is turned into a comment (aka it only works when I delete lines off a file that was already created before execution)

is there a way to make them both work at the same time?

ps: idk if this is an obvious question for a non-beginner

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX 256

typedef struct a
{
    int quan, num, price;
    char name[100];
} ar;
ar art;

void ajt(int n)
{
    int i;
    FILE *f = fopen("stock.txt", "w");
    if (f == NULL)
        return;
    for (i = 1; i <= n; i  )
    {
        printf("name of the product n* %d: ", i);
        scanf("%s", &art.name);
        fprintf(f, "name of the product n* %d is: %s  ", i, art.name);
        printf("number of the product n* %d: ", i);
        scanf("%d", &art.num);
        fprintf(f, "number of the product n* %d is: %d   ", i, art.num);
        printf("quantity of the product n* %d: ", i);
        scanf("%d", &art.quan);
        fprintf(f, "quantity of the product n* %d is: %d   ", i, art.quan);
        printf("price of the product n* %d:", i);
        scanf("%d", &art.price);
        fprintf(f, "price of the product n* %d is: %d   \n", i, art.price);
        printf("\n\n");
    }
}

void del()
{
    FILE *fileptr1, *fileptr2;
    char filename[40];
    char ch;
    int delete_line, temp = 1;

    printf("the name of your file: ");
    scanf("%s", filename);
    fileptr1 = fopen(filename, "r");
    ch = getc(fileptr1);

    while (ch != EOF)
    {
        printf("%c", ch);
        ch = getc(fileptr1);
    }

    rewind(fileptr1);

    printf("which product do u want to delete?  ");
    scanf("%d", &delete_line);
    fileptr2 = fopen("copy.c", "w");
    ch = getc(fileptr1);

    while (ch != EOF)
    {
        ch = getc(fileptr1);
        if (ch == '\n')
            temp  ;
        if (temp != delete_line)
        {
            putc(ch, fileptr2);
        }
    }

    fclose(fileptr1);
    fclose(fileptr2);
    remove(filename);
    rename("copy.c", filename);

    printf("\n the text file after modifications:\n");
    fileptr1 = fopen(filename, "r");
    ch = getc(fileptr1);

    while (ch != EOF)
    {
        printf("%c", ch);
        ch = getc(fileptr1);
    }
    fclose(fileptr1);
}

int main()
{
    int n;
    printf("how many products: ");
    scanf("%d", &n);
    printf("\n\n");
    ajt(n);
    del();
}

CodePudding user response：

Either close the file after creating it or call fflush(f); to flush the stream buffer to the file system. If you do not do that, data remains in memory in the process; it is not written to the file system. So the file does not contain the data yet, so opening a separate stream to it cannot read or change that data.