How to pass in function a multidimensional char array in C?

Question

This is my code and it is not working. It generate these errors when I pass char array like this grid[r][c]

[Error] use of parameter 'r' outside function body

[Error] use of parameter 'c' outside function body

It generate these errors when I pass char array like this grid[][c]

[Error] use of parameter 'c' outside function body

It generate these errors when I pass char array like this grid[][]

[Error] declaration of 'grid' as multidimensional array must have bounds for all dimensions except the first

And it runs perfectly fine when I pass this like this grid[1][2] i.e. just passing with an integer.0

I am stuck here and I don't know what to do or what not??

How to get rid of this problem?? Help Me !!!

Thanks in Advance!

void dfs(int r, int c, int pacman_r, int pacman_c, int food_r, int food_c, char grid[r][c]) {
    //logic here
}
int main(void) {
    int r, c;
    int pacman_r, pacman_c;
    int food_r, food_c;
    scanf( "%d %d", &pacman_r, &pacman_c);
    scanf( "%d %d", &food_r, &food_c);
    scanf( "%d %d", &r, &c);
    char grid[r][c];
    for( int i=0; i<r; i++) {
        scanf("%s[^\\n]%*c", grid[i]);
    }
    dfs( r, c, pacman_r, pacman_c, food_r, food_c, grid);
    return 0;
}

It's important to realize that you cannot actually pass an array to a function, regardless of what your function signature looks like. Arrays will decay to pointers to their first element in this situation. — Ed Swangren
– Ed Swangren, Commented Oct 21, 2014 at 21:04
it will work.(Should be treated as a char * instead of a 2D array.) also scanf("%s[^\\n]%*c", grid[i]); wrong. — BLUEPIXY
– BLUEPIXY, Commented Oct 21, 2014 at 21:30

ragingSloth · Accepted Answer · 2014-10-22 04:56:32Z

4

you should pass the argument as a char* then work with it as a pointer to a flattened instance of your array

void fn(char* grid, int c){
    printf("%c", (grid+n*c)[m]);
}

this will print `grid[n][m]

edited Oct 22, 2014 at 4:56

answered Oct 21, 2014 at 21:22

ragingSloth

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9 Comments

ragingSloth Over a year ago

sorry, forgot to pass it in, c is just the variable you're passing into your own function that corresponds to columns

Muhammad Noman Over a year ago

But it is still not working. It didn't print anything. My dimensions of char array are r and c and I wrote it as (grid+r*c)[c]. Am I wrong or right??

Muhammad Noman Over a year ago

So what should I do? Will you explain me??

Muhammad Noman Over a year ago

I wrote it like this printf("%c", (grid+i*j)[c]). i = the no of row i want to access and j = the no of column i want to access and c = total no of columns. It still not working and print garbage.

Muhammad Noman Over a year ago

Ok Thanks Finally Worked :)

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