12-07 Exercise 2: Function num_digits

Question

Write a function num_digits(n) that returns the number of digits in n ( a positive integer). Hint: to determine the number of digits in a number n, divide it by 10 repeatedly. when n reaches 0, the number of divisions indicates how many digits n originally had.

寫一個num_digits(n)函數 計算n有幾位數

#include <stdio.h>
int num_digits(int n)
{
   /*INSERT YOUR CODE HERE*/

   /*在這裡寫你的程式*/
   /*END OF YOUR CODE*/
}

int main(void)
{
   int n;
   scanf("%d", &n);
   printf("%d has %d digit(s)",n,num_digits(n));
   return 0;
}

Please complete this program by only insert your code between those tags:

   /*INSERT YOUR CODE HERE*/ 
   /*END OF YOUR CODE*/

Example input

12347

Example output

12347 has 5 digit(s)

Remember: You may correct the cases, but your code always be revised!

Answer 1

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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***    * ** *** *   **  * *     
*** *       ***    * ** **** count;
}

int main(void)
{
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  ***  **   *** ****  ** * *    **  has %d   **  *   *  **  ***
**** ** * **  *    ** *****  ** **    0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

int main(void)
{
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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 3

Hidden content!
#include    * **  * *** ** 
#include * *** *** *
int num_digits(int n)
{
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}



int main(void)
{
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}

Comments

prog.c: In function 'num_digits':
prog.c:8:6: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
    n=abs(n);
      ^~~

Answer 4

Hidden content!
#include  ******  ** ****
#include ***    ** ****  * *  
int is_prime(int n)
{
*    * ****    *        * divisor;
if (n<=1)
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for (divisor   * ** *  **  *****      *  
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return true;
}
int main(void)
{
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**  **     ***    * * (is_prime(n)) ** ** *   ****  ***        ***   * * * ***** **** function return 1
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* *   *  **  **  *   * * ***    *****  *    **     ** *** * * **
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}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 5

Hidden content!
#include   *  * *** *
int num_digits(int n)
{
 * * *** ***  *  ***    * 
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}

int main(void)
{
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* *    ***  *  *  *    *** 0;
}

Comments

prog.c: In function 'num_digits':
prog.c:7:6: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
    n=abs(n);
      ^~~
prog.c:8:16: warning: implicit declaration of function 'log10' [-Wimplicit-function-declaration]
    return (int)log10(n)+1;
                ^~~~~
prog.c:8:16: warning: incompatible implicit declaration of built-in function 'log10'
prog.c:8:16: note: include '<math.h>' or provide a declaration of 'log10'

Answer 6

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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**   ***   * *  *  ***** * **  != 0)
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* * ** ***  * *   *  ***  ** * *** ****** ** * * * *** /= 10;
** ** ***** ** *** * 
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}

int main(void)
{
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** ***    **    *   ***** * *  0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
*** * **    * ***  * *      **  cnt=0;
 *    ** *    * **  ***  *** *    *  != 0)
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*  **  * *  ** * *   *  * *  *
**  * * * *  *      *  *  * ** cnt;
*      * ** **  * *  *** **     

int main(void)
{
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 * * **   *** **     * * * *** ***  **   **  has %d *    *** * *** *   
      *   * * * * **** ** *** 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}
int main(void)
{
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 *  **    ***      **** *  * *  ** **   *   has %d ***  *  ***  * *** ***** **  **
**       ***   * *** **   * 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 9

Hidden content!
int num_digits(int n)
{
 ** *    ****** * **     num_digit=0;/*INSERT YOUR CODE HERE*/
 **   **********  ***   ** * * 
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**   ** *  ***  **  **  * * * **  * ***** **** ***** 
 ***   ****** **  * * 

   *     *******     *   ** *  * **** 
**  ****** ****  * *     OF YOUR CODE*/
  ********     ***   * ** num_digit;
}

int main(void)
{
*** * ******** *   ** n;
  *  ** *    ***  **   * *** *  ***** *    **  &n);
*  ** *     *     * **  ***  *** *   has %d ****  **  *   **  ******** 
  * * *   ****      ***** **  ** 0;
}

Comments

prog.c: In function 'main':
prog.c:18:4: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    scanf("%d", &n);
    ^~~~~
prog.c:18:4: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:18:4: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:19:4: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    printf("%d has %d digit(s)",n,num_digits(n));
    ^~~~~~
prog.c:19:4: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:19:4: note: include '<stdio.h>' or provide a declaration of 'printf'

Answer 10

Hidden content!
int num_digits(int n)
{
 * ** **  * * *****   * count=0;/*INSERT YOUR CODE HERE*/
* *    * * ** **  ***  
  * **** *        *****
 ** *  ** *  *   *  **** * * * *    ** ** ***    * * ***  
* **    *  * * **  *** * * *    **  * *  *  * * *****
   *  *  *   *****  

   ******** * *    ** ** ***  *****  
    ** * * *** ******     OF YOUR CODE*/
* ***** ** ** * **  *  count;
}

int main(void)
{
** * **   ** *  **  *** * n;
 *  *    * *********  *   * ****       &n);
 *  ** *   * ****   * * * * has %d ** ***** *** ***   *  
 * *** **  **  ***** *    0;
}

Comments

prog.c: In function 'main':
prog.c:18:4: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    scanf("%d", &n);
    ^~~~~
prog.c:18:4: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:18:4: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:19:4: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    printf("%d has %d digit(s)",n,num_digits(n));
    ^~~~~~
prog.c:19:4: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:19:4: note: include '<stdio.h>' or provide a declaration of 'printf'