variable declaration in for()

[ballpointpenthief]

I recently sent some code to a friend to go over, and I was told that
c99 doesn't allow variable declarations in for()

in other words you can't do this:

for (int i; i<9; i++);

I can't see what the reason for this not being allowed.
Any comments on this?

Cheers, Matt

 

[pete]

I recently sent some code to a friend to go over, and I was told that
c99 doesn't allow variable declarations in for()

in other words you can't do this:

for (int i; i<9; i++);

I can't see what the reason for this not being allowed.
Any comments on this?

(i) needs an initializer.

 

[ballpointpenthief]

ballpointpenthief wrote:

(i) needs an initializer.

sorry, schoolboy error
for (int i=0; i<9; i++);

 

[pete]

sorry, schoolboy error
for (int i=0; i<9; i++);

Looks like valid C99 to me.
Code like that, is usually the first clue that I notice
which indicates that I'm looking at C99 code.

 

[pemo]

I recently sent some code to a friend to go over, and I was told that
c99 doesn't allow variable declarations in for()

in other words you can't do this:

for (int i; i<9; i++);

I can't see what the reason for this not being allowed.
Any comments on this?

With an initialiser, it's perfectly legal - the scope of 'i' ending
with the statement/compund-statement following the for(), e.g.,

for(int i = 0; i < 10; ++i)
{
// use i.
}

// the i above is out of scope here.

 

[Ben Pfaff]

I recently sent some code to a friend to go over, and I was told that
c99 doesn't allow variable declarations in for()

Your friend may be thinking of C89. This feature is new in C99.