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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*    ***   ** * ** ** *** ***  * * 
*   * ** ***       ***  *** ***      ****   * ***** *  ** 
*****  *   **    *  ****  ****   *     *** **  *  ***  /= 10;
    * ***   *** *  *  ** ***  *
** * ** * *  ******     *   *  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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   *** *     * *** * *  ** 0;
}

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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***   ** * *  *****  ***   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 *        ** * *   ****
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return true;
}
int main(void)
{
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**** ** * * * **  *    *   *** * ****     ** &n);
*  ***  ***** * **** (is_prime(n)) *   *          * ** * * *  *  ** ** **    **     *****  function return 1
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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)
{
*** *    * **   *  ***  *  
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}

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

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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*    * * *** ** *  **   
* ***** * *** *  * *  ****  **  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)
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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)
{
 **  * *  * **    *  *    count=0;
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****   *  **  * **   **   **   
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*    * *  *** *****  *  **     * ** 
**     * ** *  * * *  **
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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)
{
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**** *   * * ***    *  *       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*/
  ** * * **   * * * *   *
*  **     * *** *    
**      ***  **** **  *  * *  **      **  * ** * * *
**  * *****  *    * *      ** ***  * ** * * * ** **  *
   ** * ***        *    

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