Looking for a solution for 'expected an indented block' error

Question

I have been trying to list all the field names of a shapefile but it is showing 'expected an indented block'. What should I do?

import arcpy

fieldList = arcpy.ListFields("C:\Users\Mridul\Documents\GIS\Spring 2011\650\streets_dev.shp") 

for field in fieldList: 
print field.name + " is a type of " + field.type + " with a legth of " + field.length

rows = arcpy.UpdateCursor("C:\Users\Mridul\Documents\GIS\Spring 2011\650\streets_dev.shp", "SHAPE_len>400")  

cnt = 0

for row in rows: 
    row.STREETNAME = "OLD " + row.STREETNAME 
    rows.updateRow(row)
    cnt +=  1
    print cnt

del row 
del rows

Answer 1

Your first for loop is missing an indented block.

for field in fieldList: #<----- The next line should be indented
print field.name + " is a type of " + field.type + " with a legth of " + field.length

Like this:

for field in fieldList:
    print field.name + " is a type of " + field.type + " with a legth of " + field.length

Or if the for loop only has a single statement, you can put on the same line.

for field in fieldList: print field.name

Python uses indentation to group statements. For more info, see the python reference.

Answer 2

Also note that this line:

fieldList = arcpy.ListFields("C:\Users\Mridul\Documents\GIS\Spring 2011\650\streets_dev.shp") 

will not work unless you use "raw" notation, i.e.

fieldList = arcpy.ListFields(r"C:\Users\Mridul\Documents\GIS\Spring 2011\650\streets_dev.shp") 

or replace the backslashes with forward slashes or double backslashes:

fieldList = arcpy.ListFields("C:\\Users\\Mridul\\Documents\\GIS\\Spring 2011\\650\\streets_dev.shp") 

fieldList = arcpy.ListFields("C:/Users/Mridul/Documents/GIS/Spring 2011/650/streets_dev.shp") 

or more cleverly use:

fieldList = arcpy.ListFields("C:\Users\Mridul\Documents\GIS\Spring 2011\650\streets_dev.shp".replace("\\","/") )