Read int values from a text file in C

Question

I have a text file that contains the following three lines:

12 5 6
4 2
7 9

I can use the fscanf function to read the first 3 values and store them in 3 variables. But I can't read the rest. I tried using the fseek function, but it works only on binary files.

Please help me store all the values in integer variables.

You may get more helpful answers if you post your attempt, and explain how it's failing. — caf, Jan 05 '11 at 05:15
`fseek()` works fine on text files, but it is not clear why you'd need to use it to read the data you show. — Jonathan Leffler, Jan 05 '11 at 05:29

score 60 · Answer 1 · answered Jan 05 '11 at 05:37

60

A simple solution using fscanf:

void read_ints (const char* file_name)
{
  FILE* file = fopen (file_name, "r");
  int i = 0;

  fscanf (file, "%d", &i);    
  while (!feof (file))
    {  
      printf ("%d ", i);
      fscanf (file, "%d", &i);      
    }
  fclose (file);        
}

answered Jan 05 '11 at 05:37

Vijay Mathew

26,737
4
62
93

3

With this method you don't print the last value. Delete the first `fscanf` and put the `printf` below the `fscanf` – KKKKK Jul 22 '20 at 08:52

score 9 · Answer 2 · edited Nov 30 '15 at 10:53

9

How about this?

fscanf(file,"%d %d %d %d %d %d %d",&line1_1,&line1_2, &line1_3, &line2_1, &line2_2, &line3_1, &line3_2);

In this case spaces in fscanf match multiple occurrences of any whitespace until the next token in found.

edited Nov 30 '15 at 10:53

Md. Al Amin Bhuiyan

303
1
3
12

answered Jan 05 '11 at 04:39

MAK

26,140
11
55
86

3

Might be worth mentioning that you/he should check that he gets 7 returned from `fscanf()`, as otherwise something went wrong. – Jonathan Leffler Jan 05 '11 at 05:32

Read int values from a text file in C

2 Answers2

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