Return value of sizeof() in c?
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Why does this program gives false as output?
if(sizeof(int) > -1)
The reason is that sizeof returns size_t (unsigned), so -1 was converted to unsigned before comparing.
According to the standard:
6.3.1.8 Usual arithmetic conversions
....
Otherwise, if the operand that has unsigned integer type has rank greater or equal to the rank of the type of the other operand, then the operand with signed integer type is converted to the type of the operand with unsigned integer type.
Note that if the second operand has a greater rank, the result is different. My compiler gives true for long long :
if (sizeof(int) > -1LL)
sizeof returns size_t ( unsigned type) . You are comparing a signed int with an unsigned int . When a signed operand is compared with unsigned one, the signed operand get converted to an unsigned value.
keyword sizeof followed by ellipsis returns the number of elements in a parameter pack. The type of the result is the unsigned integral type size_t defined in the header file. So you are comparing an unsigned int with a signed int.
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