Question

The following code is producing a warning when I compile it on 32-bit systems:
1087: warning: integer constant is too large for "long" type; how can I fix this so I don’t get that warning and it works correctly on 32-bit?

A valid input for this is:

unsigned char str[] = "\x00\x17\x7c\x3a\x67\x4e\xcb\x01";

and the mypow function returns unsigned long long.

     unsigned long long high, low, nano;
     high = // line 1087
         (str[7]&0xff) * mypow(2,56) +
         (str[6]&0xff) * mypow(2,48) +
         (str[5]&0xff) * mypow(2,40) +
         (str[4]&0xff) * mypow(2, 32);
     low =
         (str[3]&0xff) * mypow(2,24) +
         (str[2]&0xff) * mypow(2,16) +
         (str[1]&0xff) * mypow(2,8) +
         (str[0]&0xff);
     nano = ((high + low)/10000000) - (unsigned long long)11644473600;
     return localtime((time_t*)&nano);

Answer 1

If you are using a constant in your code that won’t fit inside 32 bits, add an LL to the end of it so the compiler knows that it’s supposed to be a ‘long long’ type. For example, the constant at the end of the nano = line should be 11644473600LL. The current code casts the constant to a long long, but the constant itself is a regular long since there is no explicit LL suffix.