program that reads a text file and stores in each line in into a char*[]

Question

I am new to c programming. I'm writing a program that reads a text file and stores in each line in into a char*[] data structures. I know how to this with characters, but I don't know how to store each line? does it require a 2D array? thats the code I have but I get segmentation error. I'm just trying to print out I and j to check if it works. Thank you

#include <stdio.h>
#define NUMBER_LINES 400


int main()
{


    char lines[NUMBER_LINES][255];
    FILE *fp = fopen("input.txt", "r");

    if (fp == 0)
    {
       return 1;
    }
     char c;
     int i ;
     while (fscanf (fp, "%c", &c) == 1)
   {

       i = 0;
       int j;


         for (j=0; !(c=='\n'); j++){
            lines[i][j] = c;
         }
       if (c == '\n'){
        printf("%s%s\n", lines[i][j]);
         i++;
       }
       }

     return 0;
}

You need to prepare the text data, if you want to get some correct answer.. — tommybee, Sep 22 '17 at 03:19

score 1 · Accepted Answer · answered Sep 22 '17 at 00:56

You could use a matrix:

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

#define NUMBER_LINES 100

int main(void)
{
    int i = 0;
    char lines[NUMBER_LINES][255];
    FILE *fp = fopen("file.txt", "r");

    if (fp == 0)
    {
        fprintf(stderr, "failed to open input.txt\n");
        exit(1);
    }
    while (i < NUMBER_LINES && fgets(lines[i], sizeof(lines[0]), fp))
    {
        lines[i][strlen(lines[i])-1] = '\0';
        printf("\n%s", lines[i]);
        i = i + 1;
    }
    fclose(fp);
    return 0;
}

score 0 · Answer 2 · answered Sep 22 '17 at 00:32

The code :

#include "get_next_line.h"


int check_n(char *str)
{
  int   i;

  i = 0;
  while (str && str[i])
    {
      if (str[i] == '\n')
    return (i);
      i++;
    }
  return (-1);
}

char    *my_strdup_gnl(char *src)
{
  int   i;
  char  *str;
  int   ret;

  i = 0;
  if ((ret = check_n(src)) == -1)
    return (NULL);
  if ((str = malloc(sizeof(char) * ret + 1)) == NULL)
    return (NULL);
  while (i < ret)
    {
      str[i] = src[i];
      i++;
    }
  str[i] = '\0';
  return (str);
}

char    *boucle_gnl(char *line, char *buff, int ret, int i)
{
  strcat(line, buff);
  i = 0;
  while (buff[ret + 1] != '\0')
    {
      buff[i] = buff[ret + 1];
      i++;
      ret++;
    }
  buff[ret] = 0;
  while (i < READ_SIZE + 1)
    {
      buff[i] = '\0';
      i++;
    }
  return (line);
}

char    *boucle_else_gnl(char *line, char *buff, int ret, int fd)
{
  int   i;
  i = 0;
  line = =strcpy(line, buff);
  while (i < READ_SIZE + 1)
    {
      buff[i] = '\0';
      i++;
    }
  if ((ret = read(fd, buff, READ_SIZE)) <= 0)
    return (NULL);
  return (line);
}

char        *get_next_line(const int fd)
{
  static char   buff[READ_SIZE + 1] = {'\0'};
  char      *line;
  int       ret;
  int       i;
  int       tmp;

  i = 0;
  tmp = 0;
  line = NULL;
  if (!buff[0] && (ret = read(fd, buff, READ_SIZE)) <= 0)
   return (NULL);
  while (tmp++ != -1)
    {
      if ((line = my_realloc(line, (tmp * READ_SIZE))) == NULL)
    return (NULL);
      if ((ret = check_n(buff)) != -1)
    return (line = boucle_gnl(line, buff, ret, i), line);
      else
    {
      if ((line = boucle_else_gnl(line, buff, ret, fd)) == NULL)
        return (NULL);
    }
    }
  return (NULL);
}

The "my_realloc function" :

char    *my_realloc(char *buff, int nb)
{
  char  *buf2;
  int   i;

  i = 0;
  if ((buf2 = malloc(sizeof(char) * (strlen(buff) + nb + 1))) == NULL)
    return (NULL);
  if (buff == NULL)
    {
      buf2[0] = '\0';
      return (buf2);
    }
  while (buff[i])
    {
      buf2[i] = buff[i];
      i++;
    }
  buf2[i] = '\0';
  return (buf2);
}

The "get_next_line.h" :

#ifndef GET_NEXT_LINE_H_
# define GET_NEXT_LINE_H_

#ifndef READ_SIZE
# define READ_SIZE 10000

#include <unistd.h>
#include <stdlib.h>

#endif /* !READ_SIZE */

#endif /* !GET_NEXT_LINE_H_ */

program that reads a text file and stores in each line in into a char*[]

2 Answers2