How to only get numbers from a file with spaces in C

Question

How can I get only the first 100 numbers(negative, integers, and floats) from a file that has numbers, spaces, and characters.

I was using this at the moment, but I think fgets is not the best command to use for this.

int readFile (FILE* fp)
{

char number[101] = "test";
//printf ("%s\n", number);
fgets(number, 101, fp);
//fscanf(fp, "%s", number);
printf ("%s", number);

return 0;
}

I suppose this current method could be used if spaces and unwanted characters were deleted, but currently this is not even working unless there are no spaces in the file.

here is an example of a file

44.5 -55 93942 11 text     text text 333.55 999999999999 1111

*unless there are no spaces in the file* How would you parse a file containing no spaces ? — cnicutar, Apr 07 '13 at 11:01
If the file has a specific format, then you have to parse it according to that format. Can you perhaps show how this file looks like, or a least a part of it? — Some programmer dude, Apr 07 '13 at 11:02
@cnicutar The same way you'd parse a file containing no dollar signs, perhaps? — autistic, Apr 07 '13 at 11:09

score 2 · Answer 1 · answered Apr 07 '13 at 11:22

2

You can use fgets to get the line, then use sscanf to extract the data needed:

double d1, d6;
int i2, i3, i4, i8;
long long ll7;

sscanf(input, "%lf %d %d %d %*s %*s %*s %lf %lld %d", &d1, &i2, &i3, &i4, &d6, &ll7, &i8);

answered Apr 07 '13 at 11:22

Some programmer dude

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score 2 · Accepted Answer · answered Apr 07 '13 at 11:47

2

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

int readFile (FILE* fp){
    char buff[4096];

    while(NULL!=fgets(buff, sizeof(buff), fp)){
        char *number, *check;
        for(number=buff;NULL!=(number=strtok(number," \t\n"));number=NULL){
            //separate string by strtok, isNumber check by strtod 
            strtod(number, &check);
            if(*check=='\0'){
                printf("%s\n",number);
            }
        }
    }

    return 0;
}

int main(){
    readFile(stdin);

    return 0;
}

answered Apr 07 '13 at 11:47

BLUEPIXY

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This works but I don't understand the really how this is working. Would you mind explaining it more? – 0x41414141 Apr 08 '13 at 07:23
@bh3244 Did you see by examining the library function (strtok , strtod) ? Briefly , strtok return every call a pointer to the string that was cut in part by a delimiter string to the specified string. strtod that convert string to double, second argument (by pointer) indicates the position where it had to be able to be parsed correctly point. Indicates that the string could be interpreted as a number that the pointer to the end that points to the location of the '\ 0' is the end of the string. I may not be described well. A proper explanation, read the description of the library. – BLUEPIXY Apr 08 '13 at 08:20

score 0 · Answer 3 · edited May 23 '17 at 12:34

0

Use fgets to parse the file contents in a single array of chars, then strtok() that for each number.
Each number you store in a double with the coresponding function. Check this out to see how you can do that.

edited May 23 '17 at 12:34

Community

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answered Apr 07 '13 at 11:13

kundrata

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How to only get numbers from a file with spaces in C

3 Answers3