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

Originally Posted by Elysia

Do not use atoi/atol; use strtol.

Hey Elysia,

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

Code:

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

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

Originally Posted by Elysia

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

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."

Originally Posted by Elysia

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

Hey Elysia,

Thanks for it.

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

Best,

Qing

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.