A question about using "fscanf_s" to read data in the txt file.

Quote:

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Originally Posted by Elysia

Do not use atoi/atol; use strtol.

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Hey Elysia,

I used your proposed statement in the following way, i.e.

Code:

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if (strtol(_temp, NULL, 10))               
{
  number = strtol(_temp, NULL, 10);
}

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There is no error raised when the value actually exceeds the limitation, instead after the conversion, the value of "number" is "2147483647".

In above example, _temp is "8729348702983457023894" read from the txt data file.

Bests,

Qing

As the manual says, it returns LONG_MAX if an overflow occurs. C functions do not throw errors.

Quote:

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Originally Posted by Elysia

As the manual says, it returns LONG_MAX if an overflow occurs. C functions do not throw errors.

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What do you mean by "throw errors?" I see no exception handling in the example.

At any rate, strtol() most certainly does inform you if the value under- or overflowed, by setting errno to ERANGE.

And many standard functions return special values to indicate "error."

Quote:

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Originally Posted by Elysia

As the manual says, it returns LONG_MAX if an overflow occurs. C functions do not throw errors.

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Hey Elysia,

Thanks for it.

I fix the problem, i.e. by using LONG_MAX and LONG_MIN.

Best,

Qing

Quote:

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Originally Posted by brewbuck

What do you mean by "throw errors?" I see no exception handling in the example.

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It was in response to

Quote:

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There is no error raised...

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I don't know if that was meant to refer literally to the raising/throwing of an exception, but just an indication of error state. The OP can certainly check whether overflow occurred by seeing if errno == ERANGE.

I was referring more to the point that the OP was expecting some "magic" to happen when overflow occurred. Which it obviously doesn't.
Checking for the error in errno == ERANGE is the error checking, not some "magic".