Thread: seperating initialising and printing of arrays into functions

Hello all,

I was trying to learn some C programming skills. Presently I am just doing very basic stuff. I created a 2d array, which is defined by the user with scanf. I am able to initialise the array and print the array when this is done in the same function. However i am unable to initialise and print the array when I seperate these two tasks into 2 seperate function.

I have only a limited understanding of how arguments are passed to array(I surprised myself when I actually got my one function to work).

Here is an outline of the code:

Code:

#include<stdio.h>

int print_array();
in_initialise_array();

main(){

int rows;
int columns;
scanf("%d %d", &rows, &columns);

initialise_array(rows, columns);

/*print_array(rows, columns);*/
}


int initialise_array(x, y)
{
char matrix[x][y];
int i, j;

for(i=0;i<x; i++)
 for(j=0; j<y; j++)
  matrix[i][j]='*';


for(i=0;i<x; i++)
 {
   for(j=0;j<y;j++)
    {
      printf("%c ", matrix[i][j]);
     }
   printf("\n");
 }
}


int print_array(x, y)
{
int i, j;

char matrix[x][y];

for(i=0;i<x; i++)
 {
   for(j=0;j<y;j++)
    {
      printf("%c ", matrix[i][j]);
     }
   printf("\n");
 }

}

If there are any typos, appologies, I couldnt work out how to copy from my VMware into this message board. I had to type this in manually from my VMWare session

A couple of thing:

1. The argument in the functions(Icalled them x and y) I can call these anything right? C will know in the line:

Code:

print_array(rows, columns)

that x is rows and y is columns?

2. I suspect i dont have to declare the array matrix a second time in print_array().

When I tried to seperate out the 2 function it would not print properly.

Can anyone give me an insight please?

After I corrected the typo on line 4, I got this output:

Code:

[root~/C] ./a.out
3 3
* * * 
* * * 
* * *

In answer to some of your questions:

• no, the variable names in the function call and the function preamble don't have to match
• no, there is no point in declaring a new matrix in print_array

However, you need to pass a pointer to the matrix to the print_array function, or there will be no matrix to do anything with.
Also, since you are not returning any values from your functions, you should declare them void:

Code:

void print_array();
void initialise_array();

The actual preamble should match.