Sum from argv

命令行求和

≈ 15 min · python-cmdline · Open in WolfCode

argv items are strings. int(x) + int(y) is required — x + y concatenates.

Python · runnable

def sum_args(argv):
    if len(argv) < 2:
        return None
    return int(argv[0]) + int(argv[1])

print(sum_args(["2", "3"]))       # 5
print(sum_args(["10", "20"]))     # 30
print(sum_args(["100", "-50"]))   # 50
print(sum_args(["1"]))            # None
print(sum_args([]))               # None

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Verify the bug yourself

# Wrong — string concat:
print("2" + "3")          # "23"
print(type("2" + "3"))    # str

# Right:
print(int("2") + int("3"))         # 5
print(type(int("2") + int("3")))   # int

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