Parse CSV file of strings into a 2d array of strings

Question

I have a CSV of strings that looks like so:

"","Orange","","","","","","Red",""
"Orange","","Blue","","","","","Black",""
"","Blue","","Pink","","Any","","","Any"
"","","Pink","","Green","Red","","",""
"","","","Green","","Blue","","",""
"","","Any","","BLue","","Orange","",""
"","","","Red","","Orange","","Green","Black"
"Red","Black","","","","","Green","","Yellow"
"","","Any","","","","Black","Yellow",""

and I would like to place it into a 2d array of strings (I'll ignore the quotation marks later). I've tried many different ideas but can't seem to get any to work properly.

This code is close but the output is off in a way I can't make sense of. It also parses and tokenizes the file correctly. It seems to go bad when it puts the tokens into the array. Here is the code taken from my program:

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

 #define VERTICES 9

 int main(void)
 {
     const char *colors[VERTICES][VERTICES];

     char buffer[1024];
     char *record, *line;
     int i = 0;
     int j = 0;
     FILE *fstream = fopen("Colors.dat", "r");
     if (fstream == NULL)
     {
         printf("\n file opening failed\n");
         return -1;
     }
     while ((line = fgets(buffer, sizeof(buffer), fstream)) != NULL)
     {
         record = strtok(line, ",");
         while(record != NULL)
         {
             printf(" %s", record);
             colors[i][j] = record;
             //printf(" %s"), colors[i][j];
             record = strtok(NULL, ",");
             j++;
         }
         j = 0;
         ++i;
     }

     printf("\n============================================\n\n");

     for (i = 0; i < VERTICES; i++)
     {
             for (j = 0; j < VERTICES; j++)
             {
                 printf("%s | ", colors[i][j]);
             }
         printf("\n");
     }
     return 0;
 }

If you uncomment the line in the second nested while loop and comment out the two for loops you get odd output as well. Thanks!

Maybe something like colors[i][j] = record; --> colors[i][j] = strdup(record);? colors, as now used, is just fill with pointers into buffer. — chux
– chux, Commented Jun 9, 2016 at 20:20
@chux Wow, that might have done it. Do you want to put that up in an answer? — ddschmitz
– ddschmitz, Commented Jun 9, 2016 at 20:24

chux · Accepted Answer · 2016-06-09 20:36:18Z

1

OP is simple recording the address of the read buffer, which gets updated on subsequent reads.

Need to allocate/copy the strings for later use.

// colors[i][j] = record;
colors[i][j] = strdup(record);

The remaining colors[i][j] in a line should be set to NULL.

     while(j < VERTICES && record != NULL) {
         printf(" %s", record);
         colors[i][j] = strdup(record);
         assert(colors[i][j]);
         record = strtok(NULL, ",");
         j++;
     }
     while(j < VERTICES) {
         colors[i][j] = NULL;
         j++;
     }

Robust code would also check for allocation failures (assert(colors[i][j]) and would free the memroy when done.

answered Jun 9, 2016 at 20:36

chux

158k17 gold badges160 silver badges311 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Parse CSV file of strings into a 2d array of strings

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related