Thread: Searching a specific string/word/etc in a text file?

I am learning the joys of text file manipulation with C and having a blast However I am having issues trying to find information online on how to search (specifically a string in my case) in a text file. Do I need to use a certain function, or use a for loop to loop through the text file and find it? I am kinda lost. Any help would be greatly appreciated

Depending on the target string ie if it's a regexp; you can make use of the regcomp() and regexec() functions.

Hmm. I think this is a bit more complex than what I'm needing. What about searching a text file for one or two words the user inputs (which would be a string in my case - but generally I'm just needing to know the basics of searching and finding something in a text file)?

Originally Posted by zacharyrs

Hmm. I think this is a bit more complex than what I'm needing. What about searching a text file for one or two words the user inputs (which would be a string in my case - but generally I'm just needing to know the basics of searching and finding something in a text file)?

1) Get the target word from the user, and open the file

2) While the file has more contents in it

3) Input a portion of the file into a char array[]

4) Use strstr() to search the array for the target word(s)

5) End the loop when the target has been found, or the file has no more content. Your choice.

6) Close the file

That's the simplest way to do it. The code is almost simpler to write out than the above description.

Instead of trying to tell us how easy it should be, why not put your time and effort into something constructive?

There are *much* more complex ways of doing what you want to do. Very smart programmers have devoted a great deal of time, finding out how to do this, better.

The above description is as simple as possible in C, and most likely, entirely meets your needs.

I too am having the same problem.

I addressed it the way Adak mentioned, using strstr. It worked and was easy to implement.

However, using strstr returns even partial matches, which I can't have. e.g. Searching for "the" returns matches on "there" and "therefore" for instance, which is not ideal.

I attempted to use sscanf to parse the string returned by fgets, then compare using strcmp, but it stops immediately upon reaching the first whitespace!

For instance, my code:

Code:

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

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

  char line_storage[100], buffer[100];
  int check, line_num = 1;
  FILE *input = fopen(argv[1], "r");
  
  while( fgets(line_storage, sizeof(line_storage), input) != NULL )  {
    check = 0;
    sscanf(line_storage,"%s",buffer);
    if(strcmp(buffer,argv[2]) == 0)  check = 1;
    if(check == 1) printf("Word found on line %d ", line_num);
    line_num++;
  }

  return 0;
  
}

correctly scans the input text file, but when it reaches sscanf it only parses the first word and then stops.

Is there any way to use sscanf to parse each word in the array line_storage, moving them to buffer and comparing against the test word?