- Trending Categories
- Data Structure
- Networking
- RDBMS
- Operating System
- Java
- iOS
- HTML
- CSS
- Android
- Python
- C Programming
- C++
- C#
- MongoDB
- MySQL
- Javascript
- PHP
- Physics
- Chemistry
- Biology
- Mathematics
- English
- Economics
- Psychology
- Social Studies
- Fashion Studies
- Legal Studies

- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who

# Count numbers with same first and last digits in C++

We are given an interval [first, last]. The goal is to find the count of numbers that have the same first and last digit within this interval. For example, 232 has the same first and last digit as 2.

We will do this by traversing from i=first to i=last. For each number I compare its first digit with the last digit, if they are the same increment the count.

Let’s understand with examples.

**Input** − first=8 last=40

**Output** − Count of numbers with same first and last digits − 5

**Explanation** − Numbers between 8 and 40 with same first and last digit −

8, 9, 11, 22, 33

**Input** − first=100 last=200

**Output** − Count of numbers with same first and last digits: 5

**Explanation** − Numbers between 100 and 200 with same first and last digit −

101, 111, 121, 131, 141, 151, 161, 171, 181, 191.

## Approach used in the below program is as follows

We take two integers first and last to define range [first,last].

Function getFirstDigit(int num) takes a number and returns its first digit.

While num>=10, divide num by 10. In the end num will have the first digit. Return this value.

Function getCount(int fst,int lst) takes range variables and returns the count of numbers with the same first and last digits.

Take the initial count as 0.

Using for loop start from i=fst to i=lst, for each i calculate it first digit by calling getFirstDigit(i) and store in fdigit. (fdigit=getFirstDigit(i)).

Calculate last digit as ldigit=i%10.

If ldigit==fdigit, means they are the same. Increment count.

Return count as result.

## Example

#include <bits/stdc++.h> using namespace std; //to find starting digit int getFirstDigit(int num){ while (num >= 10) { num = num/ 10; } return num; } int getCount(int fst,int lst){ int count=0; for(int i=fst;i<=lst;i++){ int fdigit=getFirstDigit(i); int ldigit=i%10; //to get last digit if(fdigit==ldigit) //if both are equal increment count { ++count; } } return count; } int main(){ int first = 10, last = 23; cout<<"Numbers with same first and last digits:"<<getCount(first, last); return 0; }

## Output

If we run the above code it will generate the following output −

Numbers with same first and last digits:2

- Related Articles
- Count substrings with same first and last characters in C++
- Count Numbers with Unique Digits in C++
- C++ code to count number of lucky numbers with k digits
- Numbers With Repeated Digits in C++
- Display records where first and last name begins with the same letter in MySQL
- Count even length binary sequences with same sum of first and second half bits in C++
- Count of Numbers in Range where first digit is equal to last digit of the number in C++
- Find last k digits in product of an array numbers in C++
- Maximum length of the sub-array whose first and last elements are same in C++
- Count Numbers in Range with difference between Sum of digits at even and odd positions as Prime in C++
- Absolute difference between the first X and last X Digits of N?
- First and Last Three Bits in C++
- Count characters with same neighbors in C++
- Count subarrays with same even and odd elements in C++
- Count Numbers with N digits which consists of even number of 0's in C++