C++ Program to Swap Two Numbers Using Reference with Explanation
C++
Medium
Functions
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1 min read
178 words
This problem helps you practice core C++ fundamentals in a practical way. It builds intuition around two, reference, swap. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Swap two variables using pass by reference.
Real Life: Like exchanging positions of two objects.
Input Format
Two integers a and b.
Output Format
Values of a and b after swapping.
Constraints
• Use pass by reference
• No third variable restriction is optional
Concept Explanation
Pass by reference allows a function to work on the original variables,
so changes inside the function affect values in main().
Step-by-Step Logic
1.Define a function swap(int &x, int &y).
2.References x and y point to original variables a and b.
3.Inside the function:
• Store x in a temporary variable.
• Assign y to x.
• Assign temporary value to y.
4.Function ends.
5.Values in main() are already swapped.
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
void swapNumbers(int &a, int &b) {
int temp = a;
a = b;
b = temp;
}
void function_q9_pass_by_reference() {
int x = 10, y = 20;
cout << "Before swap: x = " << x << ", y = " << y << endl;
swapNumbers(x, y);
cout << "After swap: x = " << x << ", y = " << y << endl;
}
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Solution Guide
Problem
Swap two variables using pass by reference.
Real Life: Like exchanging positions of two objects.
Input / Output
Input
Two integers a and b.
Output
Values of a and b after swapping.
Constraints
• Use pass by reference
• No third variable restriction is optional
Explanation
Concept Explanation
Pass by reference allows a function to work on the original variables,
so changes inside the function affect values in main().
Step-by-Step Explanation
1.Define a function swap(int &x, int &y).
2.References x and y point to original variables a and b.
3.Inside the function:
• Store x in a temporary variable.
• Assign y to x.
• Assign temporary value to y.
4.Function ends.
5.Values in main() are already swapped.
Details
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Official Solution
void swapNumbers(int &a, int &b) {
int temp = a;
a = b;
b = temp;
}
void function_q9_pass_by_reference() {
int x = 10, y = 20;
cout << "Before swap: x = " << x << ", y = " << y << endl;
swapNumbers(x, y);
cout << "After swap: x = " << x << ", y = " << y << endl;
}
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