Detect if two integers have opposite signs Last Updated : 12 Mar, 2025 Summarize Comments Improve Suggest changes Share Like Article Like Report Given two integers a and b, the task is to determine whether they have opposite signs. Return true if the signs of the two numbers are different and false otherwise.Examples:Input: a = -5, b = 10Output: trueExplanation: One number is negative and the other is positive, so their signs are different.Input: a = 7, b = 15Output: falseExplanation: Both numbers are positive, so their signs are the same.Input: a = 99, b = -112Output: trueExplanation: One number is negative and the other is positive, so their signs are different.Table of ContentUsing XOR Operator - O(1) Time and O(1) SpaceUsing Relational Operator - O(1) Time and O(1) SpaceUsing XOR + Right Shift Operator - O(1) Time and O(1) SpaceUsing Multiplication Operator - O(1) Time and O(1) SpaceUsing XOR Operator - O(1) Time and O(1) SpaceThe idea is that XOR (^) between two numbers with opposite signs will always have its leftmost (sign) bit set to 1. This means that if (a ^ b) < 0, then a and b have opposite signs. C++ // C++ program to check if two integers have opposite signs #include <bits/stdc++.h> using namespace std; // Function to check if two numbers have opposite signs bool haveOppositeSigns(int a, int b) { // Using XOR to check if signs are different return (a ^ b) < 0; } int main() { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { cout << "true" << endl; } else { cout << "false" << endl; } return 0; } Java // Java program to check if two integers have opposite signs class GfG { // Function to check if two numbers have opposite signs static boolean haveOppositeSigns(int a, int b) { // Using XOR to check if signs are different return (a ^ b) < 0; } public static void main(String[] args) { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { System.out.println("true"); } else { System.out.println("false"); } } } Python # Python program to check if two integers have opposite signs # Function to check if two numbers have opposite signs def haveOppositeSigns(a, b): # Using XOR to check if signs are different return (a ^ b) < 0 if __name__ == "__main__": a, b = -5, 10 if haveOppositeSigns(a, b): print("true") else: print("false") C# // C# program to check if two integers have opposite signs using System; class GfG { // Function to check if two numbers have opposite signs static bool haveOppositeSigns(int a, int b) { // Using XOR to check if signs are different return (a ^ b) < 0; } public static void Main() { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { Console.WriteLine("true"); } else { Console.WriteLine("false"); } } } JavaScript // JavaScript program to check if two integers have opposite signs // Function to check if two numbers have opposite signs function haveOppositeSigns(a, b) { // Using XOR to check if signs are different return (a ^ b) < 0; } let a = -5, b = 10; if (haveOppositeSigns(a, b)) { console.log("true"); } else { console.log("false"); } Outputtrue Using Relational Operator - O(1) Time and O(1) SpaceThe idea is to use a ternary condition to explicitly check whether one number is negative and the other is non-negative. If a is negative, we check if b is non-negative; otherwise, we check if b is negative. C++ // C++ program to check if two integers have opposite signs #include <bits/stdc++.h> using namespace std; // Function to check if two numbers have opposite signs bool haveOppositeSigns(int a, int b) { // Checking signs using relational operator return (a < 0) ? (b >= 0) : (b < 0); } int main() { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { cout << "true" << endl; } else { cout << "false" << endl; } return 0; } Java // Java program to check if two integers have opposite signs class GfG { // Function to check if two numbers have opposite signs static boolean haveOppositeSigns(int a, int b) { // Checking signs using relational operator return (a < 0) ? (b >= 0) : (b < 0); } public static void main(String[] args) { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { System.out.println("true"); } else { System.out.println("false"); } } } Python # Function to check if two numbers have opposite signs def haveOppositeSigns(a, b): # Checking signs using relational operator return (a < 0) if (b >= 0) else (b < 0) if __name__ == "__main__": a, b = -5, 10 if haveOppositeSigns(a, b): print("true") else: print("false") C# // C# program to check if two integers have opposite signs using System; class GfG { // Function to check if two numbers have opposite signs static bool haveOppositeSigns(int a, int b) { // Checking signs using relational operator return (a < 0) ? (b >= 0) : (b < 0); } public static void Main() { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { Console.WriteLine("true"); } else { Console.WriteLine("false"); } } } JavaScript // Function to check if two numbers have opposite signs function haveOppositeSigns(a, b) { // Checking signs using relational operator return (a < 0) ? (b >= 0) : (b < 0); } let a = -5, b = 10; if (haveOppositeSigns(a, b)) { console.log("true"); } else { console.log("false"); } Outputtrue Using XOR + Right Shift Operator - O(1) Time and O(1) SpaceThe idea is to first compute a ^ b, which results in a negative number if a and b have opposite signs. Then, we right shift it by 31 (for 32-bit integers) to check the sign bit. If the result is 1, it means the numbers have opposite signs; otherwise, they do not. C++ // C++ program to check if two integers have opposite signs #include <bits/stdc++.h> using namespace std; // Function to check if two numbers have opposite signs bool haveOppositeSigns(int a, int b) { // Checking signs using bitwise XOR and right shift return ((a ^ b) >> 31); } int main() { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { cout << "true" << endl; } else { cout << "false" << endl; } return 0; } Java // Java program to check if two integers have opposite signs class GfG { // Function to check if two numbers have opposite signs static boolean haveOppositeSigns(int a, int b) { // Checking signs using bitwise XOR and right shift return ((a ^ b) >> 31) != 0; } public static void main(String[] args) { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { System.out.println("true"); } else { System.out.println("false"); } } } Python # Python Program to check if two numbers have # opposite signs def haveOppositeSigns(a, b): # Checking signs using bitwise XOR and right shift return ((a ^ b) >> 31) != 0 if __name__ == "__main__": a, b = -5, 10 if haveOppositeSigns(a, b): print("true") else: print("false") C# // C# program to check if two integers have opposite signs using System; class GfG { // Function to check if two numbers have opposite signs static bool haveOppositeSigns(int a, int b) { // Checking signs using bitwise XOR and right shift return ((a ^ b) >> 31) != 0; } public static void Main() { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { Console.WriteLine("true"); } else { Console.WriteLine("false"); } } } JavaScript // Javascript Program to check if two numbers // have opposite signs function haveOppositeSigns(a, b) { // Checking signs using bitwise XOR and right shift return ((a ^ b) >> 31) !== 0; } let a = -5, b = 10; if (haveOppositeSigns(a, b)) { console.log("true"); } else { console.log("false"); } Outputtrue Using Multiplication Operator - O(1) Time and O(1) SpaceThe idea is to use multiplication to check the signs of two integers. The product of two numbers will be negative if and only if one number is positive and the other is negative. By casting the integers to a larger data type (long long, long, BigInt, etc.), we avoid overflow issues. If the product is less than zero, it means the numbers have opposite signs; otherwise, they have the same sign. C++ // C++ program to check if two integers have opposite signs #include <bits/stdc++.h> using namespace std; // Function to check if two numbers have opposite signs bool haveOppositeSigns(int a, int b) { // Checking signs using multiplication and type casting long long product = (long long) a * b; return (product < 0); } int main() { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { cout << "true" << endl; } else { cout << "false" << endl; } return 0; } Java // Java program to check if two integers have opposite signs class GfG { // Function to check if two numbers have opposite signs static boolean haveOppositeSigns(int a, int b) { // Checking signs using multiplication and type casting long long product = (long long) a * b; return (product < 0); } public static void main(String[] args) { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { System.out.println("true"); } else { System.out.println("false"); } } } Python # Python program to check if two integers # have opposite signs def haveOppositeSigns(a, b): # Checking signs using multiplication and type casting product = int(a) * int(b) return product < 0 if __name__ == "__main__": a, b = -5, 10 if haveOppositeSigns(a, b): print("true") else: print("false") C# // C# program to check if two integers have opposite signs using System; class GfG { // Function to check if two numbers have opposite signs static bool haveOppositeSigns(int a, int b) { // Checking signs using multiplication and type casting long product = (long) a * b; return (product < 0); } public static void Main() { int a = -5, b = 10; if (haveOppositeSigns(a, b)) { Console.WriteLine("true"); } else { Console.WriteLine("false"); } } } JavaScript // Javscript program to check if two // integers have opposite signs function haveOppositeSigns(a, b) { // Checking signs using multiplication and type casting let product = BigInt(a) * BigInt(b); return product < 0; } let a = -5, b = 10; if (haveOppositeSigns(a, b)) { console.log("true"); } else { console.log("false"); } Outputtrue Comment More infoAdvertise with us Next Article Swap Two Numbers Without Using Third Variable K kartik Improve Article Tags : Bit Magic DSA Bitwise-XOR Practice Tags : Bit Magic Similar Reads Bitwise Algorithms Bitwise algorithms in Data Structures and Algorithms (DSA) involve manipulating individual bits of binary representations of numbers to perform operations efficiently. 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