Put value into char 2D array

Question

I try to put value of two integers into char array. If I have:

x = 3;
y = 5;

then I want to have

links[0][0] = "3,5";

I have this code now, but I don't know how can I continue.

char** links = (char**) calloc(SRTM_SIZE, sizeof(char*));
if(links)
{
    for(int i = 0; i < SRTM_SIZE; i++)
    {
        links[i] = (char*)calloc(SRTM_SIZE, sizeof(char));
        //memset(links[i], 0, sizeof(*links[i] * SRTM_SIZE));
    }
}

x = strtok(temp, ",");
y = strtok(NULL, ",");

int xx = atoi(x);
int yy = atoi(y);

//Some calculation with x and y and if it's okay, then I need to put value of x and y to array, but I don't know how

printf("%s\n", links[0][0]);

edited:

What exactly I need is matrix (propably 1201x1201) of strings. Into cells (not into all, but propably into most of them) I need put string values. This values can be from "0,0" to "1200, 1200". And later in program I need to acces to all cells with strings values, because each value is position of one of adjacent cells.

How do you plan on using a char's space to store a string of size more than one byte? — erosenin
– erosenin, Commented Dec 29, 2013 at 18:19

The Mighty Programmer · Accepted Answer · 2013-12-29 18:36:02Z

1

use sprintf

sprintf(links[0][0],"%d,%d",x,y);

but before change links[0][0] to string(char*)

"3,5" is string not a character.

more info http://www.cplusplus.com/reference/cstdio/sprintf/

edited Dec 29, 2013 at 18:36

answered Dec 29, 2013 at 18:20

The Mighty Programmer

1,25212 silver badges24 bronze badges

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

4 Comments

haccks Over a year ago

Don't you think link[0][0] should be link[0]?

The Mighty Programmer Over a year ago

Might have you forget to see >'but before change links[0][0] to string(char*)'

haccks Over a year ago

What is this string(char*) type?

The Mighty Programmer Over a year ago

In C, String is represented/referred by char*. In this case, link[0] is of char* type but according to requirement of 'asker', link[0][0] must contains string. He needs to change its type by one level.

haccks · Accepted Answer · 2013-12-29 18:48:38Z

1

links[0][0] is of single byte. You can store only 1 byte to it ,i.e, a single character. These two characters would store into the two different memory location, say, link[0][0] and link[0][1]. Then you also need a \0 character to use %s to print them.
The statement

printf("%s\n", links[0][0]);

is wrong %s is used for strings but links[0][0] is a char.
You can do this as

sprintf(links[0], "%d,%d", xx,yy);
printf("%s\n", links[0]);

Test code after changes:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define SRTM_SIZE 5

int main(void){
    char** links = (char**) calloc(SRTM_SIZE, sizeof(char*));
    if(links)
    {
        for(int i = 0; i < SRTM_SIZE; i++)
        {
            links[i] = (char*)calloc(SRTM_SIZE, sizeof(char));
            //memset(links[i], 0, sizeof(*links[i] * SRTM_SIZE));
        }
    }

    char temp[5]="2,3";
    char *x = strtok(temp, ","); //strtok() returns pointer to char.
    char *y = strtok(NULL, ",");

    int xx = atoi(x);
    int yy = atoi(y);
    sprintf(links[0], "%d,%d", xx,yy);
    //Some calculation with x and y and if it's okay, then I need to put value of x and y to array, but I don't know how

    printf("%s\n", links[0]);

}

edited Dec 29, 2013 at 18:48

answered Dec 29, 2013 at 18:19

haccks

107k28 gold badges181 silver badges274 bronze badges

9 Comments

Sk1X1 Over a year ago

So I need to change type od my array?

Sk1X1 Over a year ago

I don't try it yet. But if I use your code, will I have in each cell one string? PS I edited my question.

haccks Over a year ago

What do you mean by each cell one string ?

Sk1X1 Over a year ago

Each cell (links[r][c]) contains char[] value from "0,0" to "1200,1200". I need save in each cell position of another cell.

haccks Over a year ago

links[r][c can contains only one character. It is links[r] which contains "0,0" or "1200,1200" string.

|

BLUEPIXY · Accepted Answer · 2013-12-29 18:30:53Z

0

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

int main(void){
    int len;
    int x = 3, y = 5;
    len = snprintf(NULL, 0, "%d,%d", x, y);
    char *link = malloc(len + 1);
    sprintf(link, "%d,%d", x, y);
    printf("%s\n", link);
    free(link);
    return 0;
}

answered Dec 29, 2013 at 18:30

BLUEPIXY

40.2k7 gold badges37 silver badges73 bronze badges

Comments

Valentin · Accepted Answer · 2013-12-29 18:31:11Z

0

You can't assign a value to a 2D array the way you do it. This is how it works:

arr[0][0]= x;

arr[0][0] refers to a single location, that is row 0, and column 0.

If you have arr[2][2], you will have to specify where you want to put your value in the 2D array. If you want it in the first row, at the last column:

arr[0][2]= x;

You may visualize a 2D array as follows:

int  arr[3][2]:

             column 0     column 1

row 0       |arr[0][0]| |arr[0][1]|
row 1       |arr[1][0]| |arr[0][1]|
row 2       |arr[2][0]| |arr[0][1]|

edited Dec 29, 2013 at 18:31

answered Dec 29, 2013 at 18:25

Valentin

6642 gold badges8 silver badges16 bronze badges

Collectives™ on Stack Overflow

Put value into char 2D array

4 Answers 4

4 Comments

9 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

4 Comments

9 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related