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|---|
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public int do_operation(int a, int b) throws ArithmeticException {
long temp = (long)a + (long)b;
if(temp >Integer.MAX_VALUE || temp < Integer.MIN_VALUE) {
throw new ArithmeticException("Not in range");
}
return (int)temp; // Value within range can perform the addition
}
|
...
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public int do_operation(int a, int b) throws ArithmeticException {
if( b>0 ? a > Integer.MAX_VALUE - b : a < Integer.MIN_VALUE - b ) {
throw new ArithmeticException("Not in range");
}
return a + b; //Value within range can perform the addition
}
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...
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|
public boolean overflow(long a, long b) {
BigInteger ba = new java.math.BigInteger(String.valueOf(a));
BigInteger bb = new java.math.BigInteger(String.valueOf(b));
BigInteger br = ba.add(bb);
return (br.compareTo(BigInteger.valueOf(Long.MAX_VALUE)) == 1 ||
br.compareTo(BigInteger.valueOf(Long.MIN_VALUE))== -1);
}
public long do_operation(long a, long b) throws ArithmeticException {
if(overflow(a,b)) {
throw new ArithmeticException("Not in range");
}
// Within range; safely perform the addition
return a + b;
}
|
...
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public int do_operation(int a,int b) {
long temp = (long)a - (long)b;
if(temp < Integer.MIN_VALUE || temp > Integer.MAX_VALUE) {
throw new ArithmeticException("Not in range");
}
return (int) temp;
}
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...
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|---|
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public int do_operation(int a, int b) throws ArithmeticException {
if( b>0 ? a < Integer.MIN_VALUE + b : a > Integer.MAX_VALUE + b ) {
throw new ArithmeticException("Not in range");
}
return a - b; //Value within range can perform the addition
}
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|---|
|
public boolean underflow(long a, long b) {
BigInteger ba = new BigInteger(String.valueOf(a));
BigInteger bb = new BigInteger(String.valueOf(b));
BigInteger br = ba.subtract(bb);
return (br.compareTo(BigInteger.valueOf(Long.MAX_VALUE)) == 1 ||
br.compareTo(BigInteger.valueOf(Long.MIN_VALUE)) == -1);
}
public long do_operation(long a, long b) throws ArithmeticException {
if(underflow(a,b)) {
throw new ArithmeticException("Not in range");
}
// Within range; safely perform the subtraction
return a - b;
}
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int a,b,result;
long temp = (long) a * (long)b;
if(temp > Integer.MAX_VALUE || temp < Integer.MIN_VALUE) {
throw new ArithmeticException("Not in range"); // Overflow
}
result = (int) temp; // Value within range, safe to downcast
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if(a == Integer.MIN_VALUE && b == -1) {
throw new ArithmeticException("Not in range"); // May be Integer.MIN_VALUE and -1
}
result = a/b; // Safe operation
|
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| Code Block |
|---|
|
if(result == Integer.MIN_VALUE) {
throw new ArithmeticException("Not in range");
}
temp = -result;
|
Absolute Value
A related pitfall is the use of the Math.abs() method that takes a parameter of type int and returns its absolute value. Because of the asymmetry between the representation of negative and positive integer values (there is an extra minimum negative value -128Integer.MAX_VALUE is 2147483647 and Integer.MIN_VALUE is -2147483648, which means there is one more negative integer than positive integers), there is no equivalent positive value (+1282147483648) for Integer.MIN_VALUE. As a result, Math.abs(Integer.MIN_VALUE) always returns a non positive Integer.MIN_VALUE.
Shifting
The shift operation in Java is quite different from C/C++,
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