Find First Match

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≈ 20 min · python-strings python-loops · Open in WolfCode

Think Python's first example of `return` inside a loop. Search pattern with early exit.

Python · runnable

def find_letter(word, letter):
    for i in range(len(word)):
        if word[i] == letter:
            return i         # found it — exit immediately
    return -1                # not found

print(find_letter("banana", "a"))    # 1
print(find_letter("banana", "z"))    # -1
print(find_letter("", "a"))          # -1

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The same shape — return the VALUE, not the index

Python · runnable

def first_word_with(words, letter):
    for w in words:
        if w.startswith(letter):
            return w
    return None

print(first_word_with(["the", "quick", "brown"], "q"))    # "quick"
print(first_word_with(["the", "quick", "brown"], "z"))    # None

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