Code snippet for comparing string field lengths using dictionaries

snippet-fieldlen-compare.py

import arcpy

srcFC = "c:/path/Geodatabase.gdb/srcFc"
destFC = "c:/path/Geodatabase.gdb/destFc"

# get field lists from each feature class, restricting to "String" feature types
srcFields = arcpy.ListFields(srcFC,"","String")
destFields = arcpy.ListFields(destFC,"","String")

# create empty dictionaries
srcDict = {}
destDict = {}

# populate dictionaries with key value pairs of field name: field length
# so that the properties can be accessed by field name
for srcField in srcFields:
    srcDict[srcField.name] = [srcField.length]

for destField in destFields:
    destDict[destField.name] = [destField.length]

# iterate through destination dictionary looking
#   for matching fields in source 
# access field lengths in dictionary by field name
# compare field lengths
for fieldName, fieldLen in destDict.items():
    if fieldName in srcDict:
        srcLen = srcDict[fieldName][0]
        destLen = destDict[fieldName][0]
        if destLen < srcLen:
            print("ERROR String field length mismatch")
            print(fieldName + " field is too long")
        else:
            print(fieldName + " all is good")