Discussion

What is the output of this C code?

void main()
    {
        int x = 1, z = 3;
        int y = x << 3;
        printf(" %d\n", y);
    }

Answer: D

Correct answer: 8

<< shifts the bits of x left by z places, and each place doubles the value:

\[ 1 \ll 3 = 1 \times 2^3 = 8 \]

So y is 8. Shifting left by \(n\) is multiplication by \(2^n\), which is why compilers turn such multiplications into shifts.

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