Question

Q1 Write a python regular expression to match a certain pattern of phone number.

            ### Suppose we want to recognize phone numbers with or without hyphens. The

### regular expression you give should work for any number of groups of any (non-

### empty) size, separated by 1 hyphen. Each group is [0-9]+.

### Hint: Accept "5" but not "-6"

### FSM for TELEPHONE NUMBER IS:

# state:1 --[0-9]--> state:2

# state:2 --[0-9]--> state:4

# state:2 --[\-]---> state:3

# state:3 --[0-9]--> state:4

# state:4 --[\-]---> state:3

# state:4 --[0-9]--> state:4

import re

regexp = ###Your Regular Expression Here.

### regexp matches:

print(re.findall(regexp,"123-4567") == ["123-4567"])

#>>> True

print(re.findall(regexp,"1234567") == ["1234567"])

#>>> True

print(re.findall(regexp,"08-78-88-88-88") == ["08-78-88-88-88"])

#>>> True

print(re.findall(regexp,"0878888888") == ["0878888888"])

#>>> True

### regexp does not match:

print(re.findall(regexp,"-6") != ["-6"])

#>>> True

Answer 1

RAW CODE

import re

regexp = '[^-][0-9-]+' ###Your Regular Expression Here.

### regexp matches:
print(re.findall(regexp,"123-4567") == ["123-4567"])
#>>> True

print(re.findall(regexp,"1234567") == ["1234567"])
#>>> True

print(re.findall(regexp,"08-78-88-88-88") == ["08-78-88-88-88"])
#>>> True

print(re.findall(regexp,"0878888888") == ["0878888888"])
#>>> True

### regexp does not match:
print(re.findall(regexp,"-6") != ["-6"])
#>>> True

SCREENSHOTS (CODE AND OUTPUT)

NOTE:- Here ' [^-] ' represents that should not start with ' - '. ' [0-9-]+ ' represents combination of numbers from 0-9 along with ' - ' anywhere in between and plus represents all the combinations except null value.

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