The "for" cyclic of question

Ken H

14y3.1k

hi friends,
Why output is 10 rather not 9.
Code:

#include
using namespace std;
void main()
{
const size_t array_size=10;
int ia[array_size];
for (size_t ix=0;ix!=array_size;++ix)
ia[ix]=ix;
cout<endl;
}

/*
my logic is:when + + X is equal to 10, you no longer perform the body of the loop statement
right result cout< output is 9,why is output is 10.
*/

thanks.

5 Replies

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Vulpes14y ago
Accepted answer
As the variable ix is scoped to the 'for' statement and not therefore available to the cout statement, I couldn't get it to compile under VC++ unless I changed it first to this:

#include
using namespace std;
void main()
{
const size_t array_size=10;
int ia[array_size];
size_t ix; /* now declared at function scope */
for (ix=0;ix!=array_size;++ix)
ia[ix]=ix;
cout<
}

It then produced a garbage result i.e. whatever is in the next memory slot after ia[9].

That's because ix will have been incremented to 10 just before the expression :

ix!=array_size

fails and the for loop exits.
Ken H14y ago
hi Hemant Srivastava,
i think this compile system question.
thanks.
Hemant Srivastava14y ago
When loop exits, at that time ix would be 10 ...right!
Now the line cout<endl; will be interpreted as cout<10]<which will be out of scope of the array (as array element would be from ia[0]... ia[9])

So accessing out of scope element "ia[10]" will give any random output. It may be 10 or something else..
Ken H14y ago
hi vulpes,

#include
using namespace std;
void main()
{
const size_t array_size=10;
int ia[array_size];
size_t ix; /* now declared at function scope */
for (ix=0;ix!=array_size;++ix)
ia[ix]=ix;
cout<}

/*
i think "cout<
*/
Hemant Srivastava14y ago
Output is coming 9.. I just checked the same program.