Why Does Adding an 'L' Suffix to Multiplication Operations Matter for Long Values?

Why Different Results from Multiplication Operations with and Without "L" Suffix?

When multiplying numbers that involve long values, adding an "L" suffix to the numeric literal is crucial for obtaining accurate results. This is because the default data type for numeric literals is int, which has a smaller range than long and can result in integer overflow.

Long Value with "L" Suffix

long oneYearWithL = 1000*60*60*24*365L;

• The literal 1000*60*60*24*365L is explicitly cast to long using the "L" suffix, ensuring that the result is stored as a 64-bit long value. This value accurately represents the number of seconds in a year.

Long Value Without "L" Suffix

long oneYearWithoutL = 1000*60*60*24*365;

• The numeric literal 1000*60*60*24*365 is implicitly cast to int since no "L" suffix is present. The result is a 32-bit integer, which overflows because the value is outside the range of int. This overflow leads to an incorrect calculation.

Binary Representation

The difference between the two values can be seen in their binary representations:

oneYearWithL  : 011101010111101100010010110000000000
oneYearWithoutL: 01111111111111111111111111111111

The "1" in the most significant bit of oneYearWithL indicates a positive value, while the "0" in the most significant bit of oneYearWithoutL indicates an overflow resulting in a negative value.

Conclusion

When multiplying numbers involving long values, explicitly using the "L" suffix ensures that the result is stored accurately as a 64-bit long value. Neglecting to add the "L" suffix can lead to incorrect calculations due to integer overflow.

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