LeetCode Problem Workspace
Return Length of Arguments Passed
Determine the number of arguments passed to a function, practicing direct counting of parameters in real-time function calls for interviews.
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Practice Focus
Easy · Return Length of Arguments Passed core interview pattern
Answer-first summary
Determine the number of arguments passed to a function, practicing direct counting of parameters in real-time function calls for interviews.
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This problem requires returning the total number of arguments provided to a function call. Focus on counting all values passed, including undefined or null entries. Understanding this ensures correct handling of variable arguments arrays and avoids common off-by-one errors in core interview scenarios.
Problem Statement
You are given a function that can accept any number of arguments. Implement a function that returns the total number of arguments passed during a call.
For example, calling the function with a single number should return 1, and calling it with multiple mixed types should return the exact count of all arguments provided. Ensure your implementation handles empty calls correctly.
Examples
Example 1
Input: args = [5]
Output: 1
argumentsLength(5); // 1
One value was passed to the function so it should return 1.
Example 2
Input: args = [{}, null, "3"]
Output: 3
argumentsLength({}, null, "3"); // 3
Three values were passed to the function so it should return 3.
Constraints
- args is a valid JSON array
- 0 <= args.length <= 100
Solution Approach
Use built-in arguments object
In most languages like JavaScript, use the 'arguments' object inside the function and return its length. This directly counts all passed parameters, matching the core pattern of returning the number of arguments.
Use rest parameters
Define the function with a rest parameter (e.g., ...args) and return args.length. This modern approach explicitly collects all arguments into an array and ensures precise counting, avoiding common mistakes with missing or extra parameters.
Validate input array
Ensure the input is treated as a proper array if arguments are passed as an array reference. Use array length to return the count, which avoids miscounting when wrapping or spreading values in calls.
Complexity Analysis
| Metric | Value |
|---|---|
| Time | Depends on the final approach |
| Space | Depends on the final approach |
Time complexity is O(1) since counting the number of arguments is immediate. Space complexity is O(1) when using the arguments object or rest parameters, and O(n) if copying arguments into a new array.
What Interviewers Usually Probe
- Wants to see understanding of variable-length argument handling.
- Checks if candidate avoids off-by-one mistakes in counting.
- Observes whether both empty and mixed-type calls are correctly handled.
Common Pitfalls or Variants
Common pitfalls
- Assuming a fixed number of parameters rather than counting all provided arguments.
- Forgetting to handle zero arguments correctly, leading to undefined or errors.
- Miscounting when using spread operators or nested arrays instead of flat arguments.
Follow-up variants
- Return the types of each argument along with the count for extended type-checking practice.
- Implement the function in a statically typed language where argument count must be inferred.
- Return the number of truthy arguments only, adding a conditional filter to the core counting pattern.
FAQ
What is the simplest way to return the length of arguments passed?
Use the 'arguments' object in JavaScript or a rest parameter and return its length, which counts all passed values accurately.
Can this function handle zero arguments?
Yes, both 'arguments.length' and a rest parameter array will return 0 when no arguments are provided.
Does the function count undefined or null arguments?
Yes, all arguments, including undefined or null, are counted when calculating the length.
How does this problem relate to interview patterns?
It tests the Return Length of Arguments Passed core interview pattern, ensuring candidates understand variable argument handling.
Can arrays or objects be passed as a single argument?
Yes, each array or object counts as a single argument regardless of its internal elements.
Solution
Solution 1
#### TypeScript
function argumentsLength(...args: any[]): number {
return args.length;
}
/**
* argumentsLength(1, 2, 3); // 3
*/