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C Exercises: Explain whether a number is Keith or not

C Numbers: Exercise-37 with Solution

Write a program in C to check if a number is Keith or not(with explanation).

Test Data
Input a number : 1537

Sample Solution:

C Code:

# include <stdio.h>
# include <stdlib.h>
# include <stdbool.h>
# include <math.h>


int lenCount(int nm)
{  int ctr=0;
    while(nm>0)
    {
        nm=nm/10;
        ctr++;
     }
     return ctr; 
}
int main()
{
    int num1=0,arr1[10],num2=0,flg=0,i=0,sum=0,kk;
	printf("\n\n Check whether a number is Keith or not: \n");
	printf(" Sample Keith numbers: 197, 742, 1104, 1537, 2208, 2580, 3684, 4788, 7385..\n");
	printf(" -----------------------------------------------------------------------\n");	
	printf(" Input a number : ");
    scanf("%d",&num1);
    num2=num1;
    for(i=lenCount(num2)-1;i>=0;i--)
    {
        arr1[i]=num1 % 10;
        num1/=10;
    }
    while(flg==0)
    {
        for(i=0;i<lenCount(num2);i++)
            sum+=arr1[i];
        if(sum==num2)
        {
            flg=1;
            kk=1;
        }
        if(sum>num2)
        {
            flg=1;
            kk=0;
        }
        for(i=0;i<lenCount(num2);i++)
        {
            printf(" %d",arr1[i]);
            if(i!=lenCount(num2)-1)
                {
				arr1[i]=arr1[i+1];
                printf(" + ");
				}
            else
                {
				arr1[i]=sum;
                printf(" = %d",arr1[i]);
				}
        }
        printf("\n");
        sum=0;
    }
            if(kk==1)
            {
            printf(" The given number is a Keith Number.\n");
            }
            if(kk==0)
            {
            printf(" The given number is not a Keith Number.\n");
            }            
}

Sample Output:

 Input a number : 1537                                                                                        
 1 +  5 +  3 +  7 = 16                                                                                        
 5 +  3 +  7 +  16 = 31                                                                                       
 3 +  7 +  16 +  31 = 57                                                                                      
 7 +  16 +  31 +  57 = 111                                                                                    
 16 +  31 +  57 +  111 = 215                                                                                  
 31 +  57 +  111 +  215 = 414                                                                                 
 57 +  111 +  215 +  414 = 797                                                                                
 111 +  215 +  414 +  797 = 1537                                                                              
 The given number is a Keith Number.

Pictorial Presentation:

C programming: Explain whether a number is Keith or not.

Flowchart:

Flowchart: Explain whether a number is Keith or not

C Programming Code Editor:

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C Programming: Tips of the Day

Why do C and C++ compilers allow array lengths in function signatures when they're never enforced?

It is a quirk of the syntax for passing arrays to functions.

Actually it is not possible to pass an array in C. If you write syntax that looks like it should pass the array, what actually happens is that a pointer to the first element of the array is passed instead.

Since the pointer does not include any length information, the contents of your [] in the function formal parameter list are actually ignored.

Ref : https://bit.ly/3fhlvdH