Put a table into memory

Question

I've to read a table from a txt file and I've to write values into memory.

I'm able to read data (row by row) from file and to put them into variables (using sscanf), but I don't know how to create and fill an array of "strings".

I need to create an array of n rows and 9 cols of strings/chars.

This code gives me a compiler warning ("warning: passing argument 1 of 'strcpy' makes pointer from integer without a cast") and the program error:

    char matrix_model_data[3][10];
    strcpy(matrix_model_data[0][0],"some text");
    printf("VALUE = %s\n",matrix_model_data[0][0]);

How can I do?

Thanks

EDIT

Now I've modified the code using my values, but it prints only the last record 1317 times (mdata_num = 1317)...why?

    char ***table = (char ***) calloc(mdata_num, sizeof(char**));

    int i, j, m;
    for(i=0; i<mdata_num; i++)
    {
        fgets(LineIn,500,fIn);
        sscanf(LineIn, "%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s",stTemp0,stTemp1,stTemp2,stTemp3,stTemp4,stTemp5,stTemp6,stTemp7,stTemp8);
        iterazioni++;
        table[i] = calloc(COLUMNS, sizeof(char*));
        for(j=0; j<COLUMNS; j++)
        {

            table[i][j] = calloc(MAX_STRING_SIZE, sizeof(char));
        }
        table[i][0] = stTemp0;
        table[i][1] = stTemp1;
        table[i][2] = stTemp2;
        table[i][3] = stTemp3;
        table[i][4] = stTemp4;
        table[i][5] = stTemp5;
        table[i][6] = stTemp6;
        table[i][7] = stTemp7;
        table[i][8] = stTemp8;
    }

    for(i=0; i<mdata_num; i++)
    {
        for(j=0; j<COLUMNS; j++)
        {
            printf("%s\t", table[i][j]);
        }
        printf("\n");
    }

    //FREE THE TABLE
    for(i=0; i<mdata_num; i++)
    {
        for(j=0; j<COLUMNS; j++)
        {
            free(table[i][j]);
        }
        free(table[i]);
    }
    free(table);

Thanks. But how can I create an array of char consisting of n rows and 9 cols? — Massimo Costanzo, Feb 21 '14 at 10:31
table[i][1] = stTemp0 just assigns the pointer, it doesn't copy the value. If you want to copy the value of stTemp0 use strncpy: srtrncpy(table[i][1], stTemp0, MAX_STRING_SIZE); — Carlos Vega, Feb 21 '14 at 14:37
Also, you can change your loop with this: http://pastebin.com/BML20aJZ — Carlos Vega, Feb 21 '14 at 14:43
Also check this out for reading lines http://stackoverflow.com/questions/3501338/c-read-file-line-by-line — Carlos Vega, Feb 21 '14 at 14:45

Carlos Vega · Accepted Answer · 2014-02-21T12:03:49.437

There are two ways, static or dynamic. Which one to use depends on whether you know the number of rows or not.

Static

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

#define ROWS 10
#define COLUMNS 9
#define MAX_STRING_SIZE 256

int main(){

  char table[ROWS][COLUMNS][MAX_STRING_SIZE];

  //EXAMPLE OF USE
  for(i=0; i<ROWS; i++)
    for(j=0; j<COLUMNS; j++)
      strcpy(table[i][j], "hi");

}

Dynamic

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

#define ROWS 10
#define COLUMNS 9
#define MAX_STRING_SIZE 256

int main(){

  char ***table = calloc(ROWS, sizeof(char**));

  int i, j;
  for(i=0; i<ROWS; i++){
    table[i] = calloc(COLUMNS, sizeof(char*));
    for(j=0; j<COLUMNS; j++){
      table[i][j] = calloc(MAX_STRING_SIZE, sizeof(char));
    }
  }

  //FREE THE TABLE
  for(i=0; i<ROWS; i++){
    for(j=0; j<COLUMNS; j++){
            fprintf(stderr, "%s, ", table[i][j]);
            free(table[i][j]);
        }
        fprintf(stderr, "\n");
        free(table[i]);
    }
    free(table);

}

Of course you need to check if the calloc calls return NULL. Allocating the strings with calloc ensures that the strings will be initialized with zeros. This algorithms will create 10 rows, with 9 columns being each column a string of 256 chars.

[Please don't cast the return value of `malloc()` and friends in C](http://stackoverflow.com/a/605858/28169). — unwind, Feb 21 '14 at 11:18

Put a table into memory

1 Answers1