What is the difference between these two syntax in c language?

Question

First syntax

int i;

for(i=0;i<5;i++)
{
  printf("Hello");
}

Second syntax

for(int i=0;i<5;i++)
{
  printf("Hello");
}

I ask my professor he said both are same but I am not satisfied with this answer.

Please tell whether he was correct or not ?

is both syntax are same or different in some aspect?

Answer 1

Both code snippets will produce the same output, but there is a difference in meaning.

In the first code snippet, the variable i will continue to exist after the for-loop, whereas in the second code snippet, the scope of the variable i is limited to the body of the for-loop.

Additionally, the second code snippet is not valid for versions of C before C99, as these did not allow the declaration of a variable inside of a for-statement.

It is generally preferred to limit the scope of variable as much as possible, as this results in simpler code.