LPC54xxx atol,atoi,strtol Redlib maximum input

[kiryat8]

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

[converse]

Why not use strtoul? This converts to unsigned long.

[kiryat8]

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

[ZhangJennie]

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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[kiryat8]

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

[kiryat8 · Accepted solution]

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.