Strok spaces using buffer/dynamic memory - c

Question

how could I strtok at spaces while reading in data from a buffer? If my text file contained
1 23 50
45 50 30
2 15 30
and I decide to print the array with my code below, it will print line by line. How could I extend this to further divide the array into individual numbers for each index of the array? Eg.
1
23
50, etc...
I've tried playing around with strtok but I keep segfaulting and I wasn't sure where to fix it.
FILE * fp;
char buffer[5000];
int size = 0;
char **entireFile = NULL;
fp = fopen("file.txt","r");
entireFile = malloc(sizeof(buffer) * sizeof(char*));
while (fgets(buffer,5000,fp)!= NULL)
{
entireFile[size] = malloc(strlen(buffer)+1);
strcpy(entireFile[size],buffer);
size++;
}

Answer 1

I want entireFile[0] = 1, entireFile1 = 23
This can easily be accomplished with fscanf. Here is a pretty good reference for scanning in inputs.
#include <stdio.h>
int main(){
FILE *in = fopen("in.txt" , "r");
int hold;
/* Won't actually store values, but can be used for
value manipulation inbetween */
while ( fscanf(in, "%d", &hold) != EOF ){
printf("Scanned in %d\n", hold);
}
fclose(in);
return 0;
}
If you want this in an array form, add an incrementing integer and change the hold to an array.
#include <stdio.h>
int main(){
FILE *in = fopen("in.txt" , "r");
int hold[100], i=0; // Hold a maximum of 100 integers
while ( fscanf(in, "%d", &hold[i]) != EOF ){
printf("Scanned in %d\n", hold[i++]);
}
fclose(in);
return 0;
}
You could also do dynamic memory allocation like this:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(){
FILE *in = fopen("in.txt", "r");
int i=0, j;
char* fragments[2000];
char entry[100];
while ( fscanf(in, "%s", &entry[i]) != EOF ){
fragments[i] = malloc(sizeof(char) * (1 + strlen(entry)));
strcpy(fragments[i], &entry[i]);
i++;
}
for ( j = 0; j < i; j++ ){
printf("%s\n", fragments[j]);
}
fclose(in);
return 0;
}

Answer 2

This will read 1, 2, or 3 numbers on each line of your file. It uses the return value from sscanf to see how many numbers were read from each line. Of course, if there is any rogue non-numerical data, it will mess up.
#include <stdio.h>
int main(void)
{
FILE *fp;
int a, b, c;
int res;
char str [100];
if ((fp = fopen("file.txt", "rt")) == NULL)
return 1;
while(fgets(str, sizeof str, fp) != NULL) {
res = sscanf(str, "%d%d%d", &a, &b, &c);
if (res == 3)
printf ("3 values %d %d %d\n", a, b, c);
else if (res == 2)
printf ("2 values %d %d\n", a, b);
else if (res == 1)
printf ("1 value %d\n", a);
else
printf ("0 values\n");
}
fclose(fp);
return 0;
}
File content:
1 23 50
45 50 30
2 15 30
10 20
100
Program output:
3 values 1 23 50
3 values 45 50 30
3 values 2 15 30
2 values 10 20
0 values
1 value 100