正则表达式匹配：排除CN开头变更通知ID的全部内容

Got it, let's break down how to solve this problem where you need to keep all entries in a comma-separated string except those with IDs starting with "CN". Each entry follows the format [ID]~-~[description], so we'll target the ID prefix specifically.

1. Using Regular Expressions (Quick Pattern Matching) #

If you just need to extract valid entries directly, a regex can handle this in one go. The pattern will match any entry where the ID doesn't start with "CN":

(?:^|,)(?!CN)\w+~-~[^,]+

How it works: #

• (?:^|,): Matches the start of the string or a comma (captures the entry's leading separator without grouping it)
• (?!CN): Negative lookahead to ensure the next characters aren't "CN"
• \w+: Matches the alphanumeric ID (adjust to [\w\d]+ if you need stricter digit/letter matching)
• ~-~: Exact match for the separator between ID and description
• [^,]+: Matches everything until the next comma (the full description part)

Example Usage (JavaScript): #

const input = "CN98765432~-~ECN for A01234 Rev A,CR00098765~-~ECR for A12345 SOME PART NAME,CN12345678~-~ECN for A12345 Rev A";
const validEntries = input.match(/(?:^|,)(?!CN)\w+~-~[^,]+/g)?.map(entry => entry.replace(/^,/, '')) || [];
console.log(validEntries.join(',')); 
// Output: "CR00098765~-~ECR for A12345 SOME PART NAME"

2. Programmatic Filtering (More Readable for Code) #

If you're working in a language like Python, splitting the string into entries and filtering is often more maintainable and easier to tweak:

Python Example: #

input_str = "CN98765432~-~ECN for A01234 Rev A,CR00098765~-~ECR for A12345 SOME PART NAME,CN12345678~-~ECN for A12345 Rev A"

# Split into individual entries
entries = input_str.split(',')

# Filter out entries where ID starts with "CN"
valid_entries = [entry for entry in entries if not entry.split('~-~')[0].startswith('CN')]

# Join back into a comma-separated string
result = ','.join(valid_entries)
print(result)
# Output: "CR00098765~-~ECR for A12345 SOME PART NAME"

Why this works: #

• Split the input string by commas to get each standalone entry
• For each entry, split on ~-~ to isolate the ID portion
• Check if the ID starts with "CN" — if not, keep the full entry
• Join the valid entries back into a single comma-separated string

Edge Cases to Consider #

• Empty Entries: If your input might have trailing commas or empty strings, add a check to skip those: if entry.strip() and not ...
• Case Sensitivity: If lowercase "cn" should also be excluded, use .lower().startswith('cn') instead
• Non-Standard IDs: If IDs can include special characters, adjust the regex or split logic to match your actual ID format

内容的提问来源于stack exchange，提问作者Some One