C Exercises: Check two given integers, each in the range 10..99. Return true if a digit appears in both numbers, such as the 3 in 13 and 33

Last update on July 28 2025 12:50:10 (UTC/GMT +8 hours)

28. Common Digit in Two Two-Digit Numbers

Write a C program to check two given integers. Each integer is in the range 10..99. Return true if a digit appears in both numbers, such as the 3 in 13 and 33.

C Code:

#include <stdio.h> // Include standard input/output library
#include <stdlib.h> // Include standard library for additional functions

int main(void){    
    printf("%d",test(11, 21)); // Call the 'test' function with arguments 11 and 21 and print the result
    printf("\n%d",test(11, 20)); // Call the 'test' function with arguments 11 and 20 and print the result
    printf("\n%d",test(10, 10)); // Call the 'test' function with arguments 10 and 10 and print the result
}       

int test(int x, int y) // Define the 'test' function that takes two integers 'x' and 'y'
{
    // Return true if any of the following conditions are met:
    // 1. x/10 equals y/10 (both have the same tens digit)
    // 2. x/10 equals y%10 (tens digit of x equals units digit of y)
    // 3. x%10 equals y/10 (units digit of x equals tens digit of y)
    // 4. x%10 equals y%10 (both have the same units digit)
    return x / 10 == y / 10 || x / 10 == y % 10 || x % 10 == y / 10 || x % 10 == y % 10;
}

Sample Output:

1
0
1

Explanation:

int test(int x, int y) {
  return x / 10 == y / 10 || x / 10 == y % 10 || x % 10 == y / 10 || x % 10 == y % 10;
}

The above function takes two integer arguments, x and y. It checks whether any of the digits of x and y are the same.

• It first checks whether the tens digit of x and y are the same.
• Then check whether the tens digit of x is the same as the ones digit of y.
• Then check whether the ones digit of x is the same as the tens digit of y.
• Finally check whether the ones digit of x and y are the same.

If any of these conditions are true, it returns 1, otherwise, it returns 0.

Time complexity and space complexity:

The time complexity of the function is O(1) since it always performs a fixed number of operations regardless of the input values.

The space complexity of the function is O(1) as the function uses a constant amount of space since it only stores two integer variables and a few temporary variables used in the calculations.

Pictorial Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to check if two two-digit numbers share any common digit, regardless of order.
• Write a C program to verify if any digit from the first two-digit number appears in the second one in reverse order.
• Write a C program that returns true if two given integers (10-99) have a sum of their digits that is identical.
• Write a C program to determine if the tens digit of one number matches the units digit of another.

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