Array size

[mohanphani2003]

Hi all,

What will happen with this code.

#include<stsio. h>
void main( )
{
int arr[3];
int i;
int j=3;
for (i=0;i<=3;i++);
{
j=j+1;
arr[i]=j;
}
}

what will be the contents on the array?

[mohanphani2003]

Can any one help me pls...

[donbock]

1. Change "stsio.h" to "stdio.h".
2. Add "printf("ar r[%d] = %d\n", i, arr[i]);" immediately after the line that assigns a value to arr[i].
3. Use CODE tags when you post code snippets on this bulletin board.

[mohanphani2003]

Thanks your suggestion is very helpful for me.

Could you pls clarify this.

Will it stores the default values or else.

[donbock]

Will it stores the default values or else.

I don't see any default values in your program. You will have to clarify what you mean.

1. Variable 'arr' is defined as an automatic variable within function 'main'. Without an initializer, the initial value of an automatic variable is unpredictable; and can be expected to be different each time you run the program.

2. Had you defined 'arr' outside of function scope, then the C Standard requires it to be initialized to all zeroes before your program was started. (But you didn't do this, so this rule doesn't apply to your program.)

3. Within your loop you assign a value to successive elements of array 'arr'. This is the only place I see where values are written into 'arr'.

By the way ... This is the Insights bulletin board. You should't post questions here. Questions should go in the answers bulletin board.

[Banfa]

Also your code writes 1 more entry into array than it actually.

[mohanphani2003]

So what will happen?

Will that extra value be stored in array or not?

[Banfa]

You will get undefined behaviour by writing outside the memory bounds of the array. Anything may happen.

You should avoid undefined behaviour at all costs, in the case of arrays it is simple, if the array is declared with a size x then the valid range for accesses to that array is 0 to x-1.

[mohanphani2003]

Thank you.

Your reply is very help ful for me.

[JosAH]

Hi all,

What will happen with this code.

#include<stsio. h>
void main( )
{
int arr[3];
int i;
int j=3;
for (i=0;i<=3;i++);
{
j=j+1;
arr[i]=j;
}
}

what will be the contents on the array?

1) most likely the file stsio.h doesn't exist so compilation will fail;
2) it's 'int main()', not 'void main()'; a pedantic compiler may object;
3) that trailing ';' after the for loop header is intentional?
4) you are writing outside of an array: that's undefined behaviour;

Was that crappy code given to you as your homework?

kind regards,

Jos

[mohanphani2003]

It's a typing mistake.Pls ignore these mistakes.I am sorry for this.