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  ** *  *    * **  * *** 
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}

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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****** ** * ***     **  ***     * *  has %d  * **  *****   **** *** **
*  * * *   *     ** 0;
}

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)
      * *    **** *   false;
for (divisor  **  * * *** ***** *   **
**  * ** *****   *   *  *
return true;
}
int main(void)
{
*  ***    ** * ***     n;
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  * **** *** *** *  * *   ***   *  *   * ** *** ***   **    * *   
** *  *    *     ** *** 0;
}

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)
{
   ****   ***   * **** *** * 
  **  ** *** * ****      ** 1;
* ****** *  ** ***
* *** *** ** *   ** * **** *
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}

int main(void)
{
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* *   **  **  ** ** ***    ******  has %d     * ** * *** ***  
* * **    *      * ** *  *  * * 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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* *****   **   * *  ****     ** *******  * * * **  ** *  ** *   
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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 7

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

* **   *** ****** ****   **  *       *** 
 ** *   ***  ** * *  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'