• 0

[C] File input and strcmp.


Question

Hello,

I am reading from a file of this format :

ID 1

name

name

name

etc.

ID 2

name

name

name

etc.

I am using fscanf to read (like this fscanf(file,"%s\n",data)), as far as I am aware fscanf will skip special characters right? So how can I understand when I get ID 1? I think it doesn't take the blank space....

Is there any other way besides reading char by char?

Thanks a lot

Link to comment
https://www.neowin.net/forum/topic/778574-c-file-input-and-strcmp/
Share on other sites

3 answers to this question

Recommended Posts

  • 0

Yes you're right. fscanf() will read whitespace and ignore it. You could maybe use something like fgets() as it will read the whole line in up to a \n

Then you can just use strcmp() to find out what the line is. Ensure you create a buffer of adequate size, however given the file you're reading in, it won't have to be that large at all.

  • 0
  ViZioN said:
Yes you're right. fscanf() will read whitespace and ignore it. You could maybe use something like fgets() as it will read the whole line in up to a \n

Then you can just use strcmp() to find out what the line is.

Cool thanks, I will try it out and report back. :)

EDIT : Ok, but if I use fgets and I reach the EOF, it will store EOF in my string variable??

How can I compare my string to an EOF?

Part of my code is like this : if (fgets(data,255,fin) != EOF

The above probably won't work though:P - would it work if I cast fgets?

Edited by gianpan
  • 0

It won't store the EOF within the string, but it will however store the \n within the string. If the EOF is encountered, fgets() returns a NULL pointer so I just checked for that.

Something like this may work:

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

int main()
{
	FILE *pFile = NULL;
	char string[100];

	pFile = fopen("text.txt", "r+");

	if(!pFile){
		printf("File cannot be opened.\n");
		return 0;
	}

	while( fgets(string, 99, pFile) != NULL){
		if(strcmp(string, "ID 1\n") == 0){
			printf("ID 1 found\n");
		}else if(strcmp(string, "ID 2\n") == 0){
			printf("ID 2 found\n");
		}
	}

	printf("\nEOF reached\n");
	getchar();

	return 0;
}

There is more information here - http://www.cplusplus.com/reference/clibrary/cstdio/fgets/

I tested it using the file

ID 1
ID 2
ID 1

Note there is a blank new line at the end of the file. This is to cope with fgets reading the \n.

You can just then modify so that once you've read an ID you can read the names. You may also want to read the file more than once so you can figure how much memory you will need to allocate to store all the names. This allows you to cope with different sizes of text file.

Hope this helps.

This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Posts

    • - What's your salary? Is it more than $100k a year? - Nah, it's $100 mil a year.
    • Compared to my ear buds which are the size of a matchbox, cover a much broader frequency range, and work everywhere without setup? Yeah, still not buying this as a replacement.
    • Meta's Superintelligence team staffed by 50% Chinese talent, 40% ex-OpenAI by Hamid Ganji Mark Zuckerberg's latest big bet at Meta involves building a team of the best AI superstars in the market to lead the so-called Superintelligence Labs. The goal of this team is to develop AI models that will ultimately lead to Artificial General Intelligence (AGI). AGI refers to an AI model with capabilities comparable to, or even beyond, those of the human brain. Achieving human-level cognitive abilities with an AI model requires substantial investments, as well as hiring the best talent to build such a system. That's why Meta is throwing hundreds of millions of dollars at AI researchers from OpenAI, Apple, and other companies to recruit them for its Superintelligence team. A user on X has now shared a spreadsheet that provides us with some unique insights into Meta's Superintelligence team and the origins of its 44 employees. The leaker claims this information comes from an anonymous Meta employee. The listing claims that 50 percent of the staff at the Superintelligence team are from China, which demonstrates the significant role of Chinese or Chinese-origin researchers in Met's AI efforts. Additionally, 75 percent of these staff hold PhDs, and 70 percent of them work as researchers. Interestingly, 40 percent of the staff are ex-OpenAI employees whom Mark Zuckerberg poached from the maker of ChatGPT. Additionally, 20 percent of Meta's Superintelligence team members come from Google DeepMind, and another 15 percent come from Scale AI, a startup that Meta recently acquired in a $15 billion deal. Another interesting point is that 75 percent of the Superintelligence team are first-generation immigrants. The leaker claims that each of these employees is now earning between $10 million and $100 million per year, although Meta still needs to confirm these substantial figures. However, it has already been reported that Meta is offering up to $100 million in signup bonuses to poach the best AI talent from OpenAI and other rivals. The revelation that half of Meta's Superintelligence team consists of Chinese nationals could trigger concerns within the Trump administration and Congress.
    • From a quick Google it seems 6GHz is optional on 802.11be. Ubiquiti has one, Unifi U7 Lite.
    • Disagreed, I feel it’s going somewhere and his role served a purpose - and moreover with maybe what 10 mins of screen time - he had a bit of character development also.
  • Recent Achievements

    • First Post
      nobody9 earned a badge
      First Post
    • One Month Later
      Ricky Chan earned a badge
      One Month Later
    • First Post
      leoniDAM earned a badge
      First Post
    • Reacting Well
      Ian_ earned a badge
      Reacting Well
    • One Month Later
      Ian_ earned a badge
      One Month Later
  • Popular Contributors

    1. 1
      +primortal
      505
    2. 2
      ATLien_0
      207
    3. 3
      Michael Scrip
      206
    4. 4
      Xenon
      139
    5. 5
      +FloatingFatMan
      114
  • Tell a friend

    Love Neowin? Tell a friend!