i thought fgets would make my program faster than if i used fgetc but because of my poor understanding on how fgets actually work my final code has alot of issues like leaving empty lines at the bottom of the file, if anyone can figure out how to fix this I’m thankful

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>

int main() {
    FILE *file, *f;
    char line[100], l[100]; // buffers to move and copy lines in the file
    int count = 1, // this counts the line we're in right now 
        StartDelete = 6, //here the first line of the sequence that we're gonna delete
        EndDelete = 10, // the line where deleting end
        size = 10; // how many lines in the file

    file = fopen("data.txt", "w+"); // Open the file in read-write mode
    f = fopen("data.txt", "r+"); // open another handle for the file to skip the lines we wanna delete 

    if (file == NULL || f == NULL) {
        printf("Error opening file.n");
        return 1;
    }

    //take user's input 
    for ( int i = 0; i < size; ++i ) {
        printf("name %d: ", i+1);
        assert( fgets( line, sizeof(line), stdin ) );
        fprintf( file, "%s%s", "name: ", line );
    }
    
    rewind(file); // going back to the start of the file 
    
    //
    while( count <= EndDelete ) {
        count++;
        fgets(l, sizeof(l), f);
    }
    count = 0;// reset the lines counter to zero this time because of the way fgets work
    // Read each line and overwrite the file with lines that are not marked for deletion
    while (fgets(line, sizeof(line), file)) { //moving to the lines in the file
        count++;//the line conter grows as we move forward in lines
        if (count > StartDelete) {
            fseek(file, -strlen(line), SEEK_CUR);//going back to the beginning of the line again because of the mechanism of fgets 
            fwrite(l, sizeof(char), strlen(l), file);//overwriting 
            if(fgets(l, sizeof(l), f));//moving to the next line we wanna overwrite with
            else break;
        }
    }

    // Truncate the file to remove any remaining content beyond the new end of file
    fseek(file, ftell(file), SEEK_SET);
    ftruncate(fileno(file), ftell(file));

    fclose(file);

    return 0;
}

i tried deleting two and three from

one
two
three
four

and i get eventually

one
four

but with extra empty line at the end