When adding contacts, an appropriate error message as shown below should be displayed if the user enters an invalid email address $($i$.$e$.,$ does not follow format, x@x$.$x$.$

When adding contacts, an appropriate error message as shown below should be displayed if the user enters an invalid phone number $($i$.$e$.,$ includes letters, or special characters other than a dash$).$

import csv

# Function to load contacts from the CSV file

def load$\_$contacts$()$:

contacts $=[]$

try:

with open$(\text{'}$contacts$.$csv$\text{'},$ mode$=\text{'}$r$\text{'})$ as file:

reader $=$ csv$.$DictReader$($file$)$

for row in reader:

contacts.append$($row$)$

print$("$Contacts file loaded."$)$

except FileNotFoundError:

print$("$No contacts found. Starting fresh."$)$

return contacts

# Function to save contacts to the CSV file

def save$\_$contacts$($contacts$)$:

with open$(\text{'}$contacts$.$csv$\text{'},$ mode$=\text{'}$w$\text{'},$ newline$=\text{'}\text{'})$ as file:

fieldnames $=[\text{'}$Name$\text{'},$ 'Email', 'Phone'$]$

writer $=$ csv$.$DictWriter$($file$,$ fieldnames$=$fieldnames$)$

writer.writeheader$()$

for contact in contacts:

writer.writerow$($contact$)$

# Function to display the command menu

def display$\_$menu$()$:

print$("$

COMMAND MENU"$)$

print$("$list $$ Display all contacts"$)$

print$("$view $$ View a contact"$)$

print$("$add $$ Add a contact"$)$

print$("$del $$ Delete a contact"$)$

print$("$exit $$ Exit program"$)$

# Function to display all contacts

def list$\_$contacts$($contacts$)$:

if not contacts:

print$("$No contacts to display."$)$

else:

for i$,$ contact in enumerate$($contacts$,$ start$=1)$:

print$($f$"\{$i$\}.\{$contact$[\text{'}$Name$\text{'}]\}")$

# Function to view a specific contact

def view$\_$contact$($contacts$)$:

try:

number $=$ int$($input$("$Number: $"))$

contact $=$ contacts$[$number $-1]$

print$($f$"$Name: $\{$contact$[\text{'}$Name$\text{'}]\}")$

print$($f$"$Email: $\{$contact$[\text{'}$Email$\text{'}]\}")$

print$($f$"$Phone: $\{$contact$[\text{'}$Phone$\text{'}]\}")$

except $($ValueError$,$ IndexError$)$:

print$("$Invalid contact number."$)$

# Function to add a contact

def add$\_$contact$($contacts$)$:

name $=$ input$("$Name: $")$

email $=$ input$("$Email: $")$

phone $=$ input$("$Phone: $")$

contacts.append$(\{\text{'}$Name$\text{'}$: name, 'Email': email, 'Phone': phone$\})$

save$\_$contacts$($contacts$)$

print$($f$"\{$name$\}$ was added."$)$

def add$\_$email$($contacts$)$:

email $=$ input$("$Email: $")$

try:

if $\text{'}.\text{'}$ not in email:

print$("$Invalid email address"$)$

elif $\text{'}$@$\text{'}$ not in email:

print$("$Invalid email address"$)$

class NonalphaError$($Exception$)$:

pass

class NondigitError$($Exception$)$:

pass

def validate$($name$,$phone$\_$no$)$:

try:

if$($name$.$isalpha$()!=$True$)$:

raise NonalphaError

if$($phone$\_$no$.$isdigit$()!=$True$)$:

raise NondigitError

except NonalphaError:

print$("$Please Enter Alphabets only"$)$

except NondigitError:

print$("$Please Enter Digits only"$)$

print$("$The contact of$",$name,"is$",$phone$\_$no$)$

finally

main$()$

# Function to delete a contact

def delete$\_$contact$($contacts$)$:

try:

number $=$ int$($input$("$Number: $"))$

contact $=$ contacts.pop$($number $-1)$

save$\_$contacts$($contacts$)$

print$($f$"\{$contact$[\text{'}$Name$\text{'}]\}$ was deleted."$)$

except $($ValueError$,$ IndexError$)$:

print$("$Invalid contact number."$)$

# Main function to run the program

def main$()$:

contacts $=$ load$\_$contacts$()$

display$\_$menu$()$

while True:

command $=$ input$("$

Command: $").$lower$()$

if command $==$ "list":

list$\_$contacts$($contacts$)$

elif command $==$ "view":

view$\_$contact$($contacts$)$

elif command $==$ "add":

add$\_$contact$($contacts$)$

elif command $==$ "del":

delete$\_$contact$($contacts$)$

elif command $==$ "exit":

break

else:

print$("$Invalid command. Try again."$)$

display$\_$menu$()$

# Start the program

if $\_\_$name$\_\_=="\_\_$main$\_\_"$:

main$()$