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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****  **    ** ***        *  *  *  i;
}

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)
{
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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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}

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)
{
* * *** * **** * **** * *  * count=0;
** ** * *  **  ***  *   *  != 0)
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*  ****   **   *  * ***** **    
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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 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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*    **    ** * *** ***** **  **   *** * &n);
*** **  * ** * * * *  ** **     *   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;
 *  * ******* * *** ***
  * * *         ** *** **      != 0)
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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*/
* ***  *  ***   ***       *    
* **   ** *    *   * ** 
* **  **** * * * *  **  ** * ***    *** **  ****       *  
*** **  *   *   ***  * *     *****      **  * ***     * **** 
***    ***  ** *  **  *** 

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