Reading from a file and storing in C

Question

I am trying to read in a text file of a string followed by a number and then store it's contents. So far I can only get it to print it out just the string (or just the int, or both) if it is properly formatted. How can I skip blank or misformatted lines lines (which currently duplicated the previous line) and also store the results?

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

#define MAX_LINE_LENGTH 400

int main ()
{
    char input[MAX_LINE_LENGTH];
    char name[MAX_LINE_LENGTH];
    int number;

    FILE *fr;
    fr = fopen ("updates.txt", "r");
    if (!fr)
    return 1;  
    while (fgets(input,MAX_LINE_LENGTH, fr)!=NULL)
    {
        /* get a line, up to 200 chars from fr.  done if NULL */
        sscanf (input, "%s", name);
        /* convert the string to just a string */
        printf ("%s\n", name);
    }
    fclose(fr);
    return 0;
}

Example text file

Cold 5
10 Flames

Doggy                      4

Flames 11
Cold 6

Answer 1

Probable solution for your problem is in the code below.

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

#define MAX_LINE_LENGTH 400

int main ()
{
    char input[MAX_LINE_LENGTH];
    char name[MAX_LINE_LENGTH];
    char namet[MAX_LINE_LENGTH];
    int number;

    FILE *fr;
    fr = fopen ("updates.txt", "r");
    if (!fr)
    return 1;
    while (fgets(input,MAX_LINE_LENGTH, fr)!=NULL)
    {
        memset(name, 0, MAX_LINE_LENGTH);
        memset(namet, 0, MAX_LINE_LENGTH);
        /* get a line, up to 200 chars from fr.  done if NULL */
        //sscanf (input, "%s %d", name, &number);
        sscanf (input, "%s %s", name, namet);

        // TODO: compare here for name shall only contain letters A-Z/a-z
        // TODO: compare here for namet shall only contain digits

        // If both above condition true then go ahead
        number = atoi(namet);

        if(name[0] != '\0')
        {
                /* convert the string to just a string */
                printf ("%s %d\n", name, number);
                //printf ("%s %s\n", name, namet);
        }
    }
    fclose(fr);
    return 0;
}

Answer 2

You may use fscanf function. A blank space in format string makes it to ignore any spaces, tabs or newlines.

Answer 3

Instead of

while (fgets(input,MAX_LINE_LENGTH, fr)!=NULL)
{
  /* get a line, up to 200 chars from fr.  done if NULL */
  sscanf (input, "%s", name);
  /* convert the string to just a string */
  printf ("%s\n", name);
}

do this (it will remove all spaces and \n and just take out the tokens)

while (fgets(input,MAX_LINE_LENGTH, fr)!=NULL)
{
  char* token = strtok(input, " \n");
  while ( token != NULL )
  {
    printf( "%s", token );
    token = strtok(NULL, " \n");
  }
}