asked on

simple c++ language question

may be this will sound realy dumb but...
when you have this code:

void f()
{
TCHAR szName[200];
ZeroMemory( szName, 200 );
}
void g()
{
static TCHAR szSurname[200];
ZeroMemory( szSurname, 200 );

}

void main()
{
for( int i = 0; i < 10 ; i++ )
{
f();
g();
}
}

how many time will szName be allocated?

thanks.
A.

Agarici

ASKER

i know that szSurname will be allocated only once
but what about szName?

jkr

Since 'szName()' is non-static, it'll be allocated on the stack ten times, that's what the loop

for( int i = 0; i < 10 ; i++ )

does for i ranging from 0...9.

SOLUTION

Linky

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Agarici

ASKER

well... that is what i also know...
i asked this because i had a dispute with a collegue of mine... and he was saying that szName will only be alocated once on the stack... with such a strong belief that made me wory...

thanks
A.

jkr

>>he was saying that szName will only be alocated once on the stack

For 'f()', that's true, but since 'f()' is called 10 times in the loop...

The key difference here is the 'static' keyword on the other local variable, which specifies that the variable has static duration (it is allocated when the program begins and deallocated when the program ends).

Agarici

ASKER

what if i have:
void f()
{
for( int i = 0 ; i < 10 ; i++)
{
TCHAR szName[200];
ZeroMemory( szName, 200 );
}
}

void main()
{
for( int i = 0; i < 10 ; i++ )
{
f();
}
}

there will be 100 allocations, corect?

ASKER CERTIFIED SOLUTION

jkr

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SOLUTION

itsmeandnobodyelse

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Agarici

ASKER

ok
thank you all for the replys
A.

rstaveley

> he was saying that szName will only be alocated once on the stack...

It gets allocated on the stack each time the function is called when it is automatic, but what your colleague may have been thinking is that the memory is released when the function exists, so the same chunk of memory will be typically be allocated each time, when you call the function in your loop.

rstaveley

s/when the function exists/when the function exits/