strtol not detecting integer overflow
Domanda
I'm trying to convert a character array into an integer using strtol using the below code:
int foo = strtol(temp, (char **)NULL, 0);
Where temp = 4000000010
However strtol does not detect the overflow, it does not set foo to LONG_MAX and errno does not change from its inital value of 0.
Instead bob is changed to the overflowed value of -294967286.
So I was wondering what am I missing here?
Soluzione
The overflow probably occurs on the implicit long
to int
conversion in your statement, not inside strtol()
.
Altri suggerimenti
If you know you will get large numbers, why not use strtoll
instead? Of course, like others remarked, then you definitively can't use an int
to store the result.
- You cannot store a variable of 4*10^9 in a 32-bit long. long is signed by default.
- The maximum value of a long is (2^32 / 2)-1 = 2147483674, assuming long is 32 bit on your system.
- Use strtoul() instead.
- Change foo to unsigned long.
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