This works for me:

    def access_table(): 
            slide = prs.slides[0] #first slide
            table = slide.shapes[2].table # maybe 0..n
            for r in table.rows:
                    s = ""
                    for c in r.cells:
                            s += c.text_frame.text + " | "
                            #to write
                            #c.text_frame.text = "example"
                    print s

How to Extract All of the Text out of Tables Inside of a Slide-show Presentation

The following code extracts text from tables in a slide-show presentation. Text in the presentation outside of tables is omitted, but you can modify my code to capture text from non-table objects as well.

import pptx as pptx
from pptx import *

def get_tables_from_presentation(pres):
   """
   The input parameter `pres` should receive
   an object returned by `pptx.Presentation()`

   EXAMPLE:
       ```
       import pptx
       p = "C:\Users\user\Desktop\power_point_pres.pptx"
       pres = pptx.Presentation(p)

       tables = get_tables_from_presentation(pres)
       ```
   """
   tables = list()
   for slide in pres.slides:
      for shp in iter(slide.shapes):
         if shp.has_table:
            table = shp.table
            tables.append(table)
   return tables


def iter_to_nonempty_table_cells(tbl):
   """
   :param tbl: 'pptx.table.Table'
          input table is NOT modified

   :return: return iterator to non-empty rows
   """
   for ridx in range(sum(1 for _ in iter(tbl.rows))):
      for cidx in range(sum(1 for _ in iter(tbl.columns))):
         cell = tbl.cell(ridx, cidx)
         txt = type("")(cell.text)
         txt = txt.strip()
         if len(txt) > 1:
            yield txt


# establish read path
in_file_path = "C:\Users\user\Desktop\power_point_pres.pptx"

# Open slide-show presentation
pres = Presentation(in_file_path)

# extract tables from slide-show presentation
tables = get_tables_from_presentation(pres)

for tbl in tables:
   it = iter_to_nonempty_table_cells(tbl)
   print("".join(it))

A Note About One of the Other Answers to This Question

Someone else posted a semi-useful answer to this question written in pseudo-code. They wrote the following:

For r = 1 to tbl.rows.count
  For c = 1 to tbl.columns.count
     tbl.cell(r,c).Shape.Textframe.Text

The problem is, that is not python.

In python, it is illegal syntax to write For r = 1 to 10
Instead, we would write something like the following:

for r in range(1, 11):
   print(r)  

from itertools import *
for r in takewhile(lambda k: k <= 10, count(1)):
   print(r)

Additionally, the row indicies start at r = 0 not r = 1

The upper-left corner of the table is tbl.cell(0,0) not tbl.cell(1,1)

There is no such thing as .count for the rows attribute or the columns attribute. (For r = 1 to tbl.rows.count) makes no sense because there is no such thing as tbl.rows.count

tbl.cell(r,c).Shape won’t work, because objects instantiated from the class pptx.table._Cell have no attribute named Shape

cell objects have the following attributes:

• fill
• is_merge_origin
• is_spanned
• margin_bottom
• margin_left
• margin_right
• margin_top
• merge
• part
• span_height
• span_width
• split
• text
• text_frame
• vertical_anchor

A fix is shown below:

# ----------------------------------------
# BEGIN SYNTACTICALLY INCORRECT CODE
# ----------------------------------------
# For r = 1 to tbl.rows.count
#   For c = 1 to tbl.columns.count
#      tbl.cell(r,c).Shape.Textframe.Text
# ----------------------------------------
# END SYNTACTICALLY INCORRECT CODE
# BEGIN SYNTACTICALLY CORRECT CODE
# ----------------------------------------
for r in range(sum(1 for row in iter(tbl.rows))):
    for c in range(sum(1 for _ in iter(tbl.columns))):
        print(tbl.cell(r,c).text)
# ----------------------------------------
# END SYNTACTICALLY CORRECT CODE
# ----------------------------------------

A Note About your Original Code

The continue keyword

In your original source code, you have the following for-loop:

for shape in slide.shapes:
    if not shape.has_text_frame:
      continue

That for-loop does not do anything.

The continue keyword simply means "increment the loop-counter and jump to the beginning of the loop" However, there is no code after your continue and before the end of the loop. That is, the loop would have continued anyway without you having to write continue because it is already at the end of the loop-body.

To understand more about continue consider the following example:

for k in [1, 2, 3, 4, 5]:
    print("For k ==", k, "we have k % 2 == ", k % 2)
    if not k % 2 == 0:
        continue
    print("For k ==", k, "we got past the `continue`")

The output is:

For k == 1 we have k % 2 ==  1
For k == 2 we have k % 2 ==  0
For k == 2 we got past the `continue`
For k == 3 we have k % 2 ==  1
For k == 4 we have k % 2 ==  0
For k == 4 we got past the `continue`
For k == 5 we have k % 2 ==  1

The following three pieces of code all print the exact same messages, regardless of the use of the continue keyword:

for k in [1, 2, 3, 4, 5]:
    print(k)

for k in [1, 2, 3, 4, 5]:
    print(k)
    continue

for k in [1, 2, 3, 4, 5]:
    print(k)
    if float(k)//1 % 2 == 0:
        continue