#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <fcntl.h>

int main(int argc, char const *argv[])

{

//FILE *file;

char name[] = "file.txt";

int strLength = 0, num, i = 0, position = 0;

int file1;

file1 = open(name, O_RDONLY);

int *lengths = NULL;

int *positions = NULL;

char buff[64];

lengths = (int*)malloc(1 * sizeof(int));

while(read(file1, buff, 1) != 0){

if (buff[0] == '\n')

{

lengths[i] = strLength;

i++;

position = lseek(file1, 0, SEEK_CUR);

positions = (int*)realloc(positions, (i+1) * sizeof(int));

lengths = (int*)realloc(lengths, (i+1) * sizeof(int));

positions[i] = position;

strLength = 0;

}else{

strLength++;

}

}

lengths[i] = strLength;

positions = (int*)realloc(positions, (i + 2) * sizeof(int));

positions[i+1] = lseek(file1, 0, SEEK_END);

do{

memset(buff, 0, 64);

printf("\nВведите номер строки\n");

scanf("%d", &num);

if(num > i+1){

printf("В файле всего %d строк(и), введите номер строки из этого диапазона\n", i+1);

}else if(num != 0){

lseek(file1, positions[num-1], SEEK_SET);

strLength = lengths[num-1];

read(file1, buff, strLength);

printf("\n%s, длина %d\n", buff, strLength);

}

} while(num != 0);

/* for (int n = 0; n < i; n++){

printf("\n%d, %d\n", positions[n], lengths[n]);

} */

close(file1);

free(positions);

free(lengths);

return 0;

}