Question

code 1:

i = 0;
while ( arr[i++] != EOF )
     printf("%d", i);

output: 1 2 3 4

code 2:

i = 0;
while ( arr[i] != EOF )
{
      printf("%d", i);
      i++;
}

output: 0 1 2 3

In the above code, arr[] = "//\n\0"

However, I assume i++ should first assign i and increment right?

i.e.,

if i = 1
j = i++
j = 1 (Not 2)

So, what exactly is happening in code 1 and why it isn’t behaving like code 2?

Answer 1

You increment i when you do this arr[i++], so when you go to print it out of course it will be incremented already.

Instead print out the array element so you know you got the right one:

i = 0;
char c;
while ( (c = arr[i++]) != EOF )
     printf("%c", c);