LPC MicrocontrollersのトピックRe: LPC54xxx atol,atoi,strtol Redlib maximum input

LPC54xxx atol,atoi,strtol Redlib maximum input

kiryat8 — Sun, 10 Mar 2019 10:06:04 GMT

I need to parse a decimal string representation of an unsigned 4 byte integer or long.

In my debugger I can see that when the 4 byte value string is 2943834865,

I get a result of 2147483647 (0x7fffffff) from atol,atoi and strtol .

fileChecksum = atol(Ptr2);
fileChecksum = strtol(Ptr2,&Ptr1,10);

The debugger:

Ptr2 -> Details:0x20002bd5 <g_bufferRead+13> "2943834865"

Name : fileChecksum
   Details:2147483647
   Default:2147483647
   Decimal:2147483647
   Hex:0x7fffffff
   Binary:1111111111111111111111111111111
   Octal:017777777777

I am guessing that this is because of an overflow from the signed value.

The fileChecksum I defined uint32_t and then as uint64_t with the same result.

Thanks

Re: LPC54xxx atol,atoi,strtol Redlib maximum input

kiryat8 — Mon, 11 Mar 2019 14:35:06 GMT

I also tried to enter the checksum string in hex format and got the same results 0x7fffffff

Today the checksum string was checksum=2939504859=0xAF3548DB.

I tried to enter "AF3548DB" with the strtol function set at base 16.

fileChecksum = strtol(Ptr2,&Ptr1,16);

There may be a linker or compiler setting.

I may just break the string into two parts but other places in my code I use the atoi,atol functions andthe problem may not have yet surfaced.

Re: LPC54xxx atol,atoi,strtol Redlib maximum input

ZhangJennie — Tue, 12 Mar 2019 07:47:06 GMT

Hi,

this function for example atol is defined as:

long int atol(const char *nptr);

Here GNU defined long max as 0x7FFFFFFF(2^31-1), so anything larger than that will out put 0x7FFFFFFF.

Have a great day,
Jun Zhang

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Re: LPC54xxx atol,atoi,strtol Redlib maximum input

kiryat8 — Tue, 12 Mar 2019 11:45:43 GMT

I knew the size of a signed long but never thought they would think to cap results that actually fit into an unsigned long.

I guess I never noticed this and will have to check the places I use atoi & atol.

Thanks

Re: LPC54xxx atol,atoi,strtol Redlib maximum input

converse — Tue, 12 Mar 2019 14:14:31 GMT

Why not use strtoul? This converts to unsigned long.

Re: LPC54xxx atol,atoi,strtol Redlib maximum input

kiryat8 — Wed, 13 Mar 2019 05:54:09 GMT

Thank you. Of course strtoul is what I was looking for. It works without problem. It makes sense to have strtoul and also strtol which I tried previously, but when you are used to the automatic conversion between signed and unsigned stuff in C, I did not think of it.

The no unsigned integers in Java is just crazy.

Thanks