CODEWITHSUNDEEP
cpointersfile-ioprintffree
jimo
jimo

Reputation: 602

Printing a line read from a file containing a particular word

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

int main()

{
  int i, p=0;;
    int c;
    char file_name[100];
    char  search[10];

    printf("Enter the file name:");
    scanf("%s", file_name);
    printf("Search word:");
    scanf("%s", search);

    FILE *f = fopen((strcat(file_name, ".txt")), "rb");
    fseek(f, 0, SEEK_END);
    long pos = ftell(f); 
    fseek(f, 0, SEEK_SET);

    char *bytes = malloc(pos + 1);
    fread(bytes, pos, 1, f);
    bytes[ pos ] = '\0'; 

/*search*/

    if (strstr(bytes, search) != NULL){
        printf("found\n");
        p = 1;}
    else{
        printf("Not found\n");

        p=0;}

    free(bytes);

   char *found = strstr( bytes, search );
   if ( found != NULL )
   {
    char *lineStart;
    for(lineStart = strchr(bytes, '\n');  !strcmp(lineStart,"\n"); 
        lineStart = strchr(lineStart+1, '\n')){
      printf("%s\n", lineStart);  
   }
  }
}

The above stated code is supposed to search for a word in a file (.txt) and if found it should print "found" and print the line it was found in. For example, if searched for a word "Brick" in the file, and if found in a sentence like "The house is made of red bricks", then it prints the whole sentence as the output i.e "The house is made of the red bricks".

I am having trouble printing the line containing the search word. I am trying to use pointer to move to the start of the current line and then navigate incrementally but I am kinda stuck in how to make the pointer stop at the end of the line and just print up till that point.

Upvotes: 1

Views: 2183

Answers (1)

Sourav Ghosh
Sourav Ghosh

Reputation: 134376

The issue with your code is, you call free(bytes); inside your code and after that, you continue to use bytes. This invokes undefined behavior.

Also, i'll suggest

  1. change your scanf() instruction

    scanf("%s", file_name);

    and

    scanf("%s", search);

    to

    scanf("99%s", file_name);

    and

    scanf("9%s", search);

    to avoid the risk of buffer overflow.

  2. Always check for the success of fopen() before using the returned pointer.

However, from the logical point, i'll suggest you

  1. Read a whole line by line from the file using fgets()
  2. Search for the particular word using strstr().
  3. If found, print the whole line, otherwise, continue to step 1 until fgets() return NULL.

Notes:

  1. the recommended signature of main() is int main(void).
  2. Always initialize all local variables.

Upvotes: 4

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