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objective-ccintegerliterals

Why write 1,000,000,000 as 1000*1000*1000 in C?

In code created by Apple, there is this line:

CMTimeMakeWithSeconds( newDurationSeconds, 1000*1000*1000 )

Is there any reason to express 1,000,000,000 as 1000*1000*1000?

Why not 1000^3 for that matter?

Solution

  • One reason to declare constants in a multiplicative way is to improve readability, while the run-time performance is not affected. Also, to indicate that the writer was thinking in a multiplicative manner about the number.

    Consider this:

    double memoryBytes = 1024 * 1024 * 1024;

    It's clearly better than:

    double memoryBytes = 1073741824;

    as the latter doesn't look, at first glance, the third power of 1024.

    As Amin Negm-Awad mentioned, the ^ operator is the binary XOR. Many languages lack the built-in, compile-time exponentiation operator, hence the multiplication.