public class ClearBitsRange {
// Print bits of a 32-bit integer
static void printBits(int x, String label) {
String bits = String.format("%32s", Integer.toBinaryString(x))
.replace(' ', '0');
System.out.println(label + ": " + bits);
}
// Clear bits in range [l, r] inclusive (0 = least significant bit)
static int clearBits(int x, int l, int r) {
if (l < 0 || r > 31 || l > r) {
throw new IllegalArgumentException("Invalid bit range");
}
// maskLeft:
// Create a mask with 1s above bit r and 0s from bit r down to 0.
// Example: r = 5 → maskLeft = 11111111 11111111 11111111 11000000
int maskLeft = ~0 << (r + 1);
printBits(maskLeft, "maskLeft ");
// maskRight:
// Create a mask with 1s below bit l and 0s from bit l upward.
// Example: l = 3 → maskRight = 00000000 00000000 00000000 00000111
int maskRight = (1 << l) - 1;
printBits(maskRight, "maskRight");
// Combine both masks:
// maskLeft keeps bits above r.
// maskRight keeps bits below l.
// The range [l, r] becomes 0s.
int mask = maskLeft | maskRight;
printBits(mask, "mask ");
return x & mask;
}
public static void main(String[] args) {
int value = 0b11111100111111001111110011111100;
int l = 3; // start bit
int r = 10; // end bit
int result = clearBits(value, l, r);
printBits(value, "Before ");
printBits(result, "After ");
}
}
/*
run:
maskLeft : 11111111111111111111100000000000
maskRight: 00000000000000000000000000000111
mask : 11111111111111111111100000000111
Before : 11111100111111001111110011111100
After : 11111100111111001111100000000100
*/
