List out of bound exception at List<Blob>

Question

I have below piece of code where I get below error. Here b is the List of blobs. Error

List index out of bounds: 3

Apex Code

for(integer i = 0; i <counter; i++)
{
   Messaging.EmailFileAttachment efa = new Messaging.EmailFileAttachment();
   efa.setFileName('attachment.pdf');
   efa.setBody(b[i]); // List index out of bounds: 3

   lstFileAttachments.add(efa);
}

Answer 1

Instead counter use b.size()

for(integer i = 0; i <b.size(); i++)
{
   Messaging.EmailFileAttachment efa = new Messaging.EmailFileAttachment();
   efa.setFileName('attachment.pdf');
   efa.setBody(b[i]);

   lstFileAttachments.add(efa);
}