Count the amount of numbers on each line in a text file-CodePudding

I am currently learning C programming (my experience is in Python, Java and Swift). I am trying to count how many numbers are on the first line of a text file.

The text file looks a bit like this:

-54 37 64 82 -98 
...

I have tried various different ideas that I have had. The first was to check each character in turn for the EOL, and if it wasn't to add 1 to the total. I quickly realised this only works for single digit numbers, and not general integers.

I then tried to use fscanf to find the last number on the line, and then rewind and use fscanf to count each number until that last number was found again:

int temp;
FILE *fd = fopen("test.txt", "r");

fscanf(fd, "%d\n", &temp);
printf("Last Number on Line is: %d\n", temp);

However before I could even write the next logic to count the numbers I realised that this printed Last Number on Line is: -54 which was not the expected output from the above file example.

At this point I am rather stuck. Searching online mainly returns results on how to count how many lines are in a file due to the similarity of the question.

Any help would be much appreciated!

CodePudding user response：

You can use the function fgets to read a line from the file. Then you can use the function sscanf to count the number of numbers in the line.

For example let's assume that you already read a line from the file and store it in the array with name s

char s[] = "1 12 123 1234 12345\n";

Now in a loop you can count the number of numbers for example the following way

    size_t count = 0;
    int pos;

    for (const char *p = s; sscanf( p, "%*d%n", &pos ) != EOF; p  = pos)
    {
          count;
    }

    printf( "count = %zu\n", count );

The output of this code snippet will be

count = 5

If you do not know the maximum size of a record in the file you can dynamically reallocate a character array until fgets will read the new line character '\n' and then apply the approach with sscanf.

CodePudding user response：

In the end I have used the suggestion here and come up with the following solution:

char buffer;
int  temp = 0;
int  row_count = 0;

while((buffer = getc(fd)) != '\n') {
    if (temp == 0 && (isdigit(buffer))) {
        col_count  = 1;
        temp = 1;
    } else if (temp == 1 && buffer == ' ') {
        temp = 0;
    }
}

This is working fine for me in the context I am using it within, thanks for the help