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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* *  **  *     ***    ** *  **  *******  ** ***** &n);
*  ***   *    *  * ** **  *** * ****     **  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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*  *  ** * * *  *** ** *  *** has %d * *     *  * * **** **   
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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)
** ** * **** *  *   false;
for (divisor *  * **   * **** ** * * *
*** * *  **  * *  ** *  
return true;
}
int main(void)
{
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* **  ******* ** ** **         ***  ** *    &n);
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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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*   *  * *** *   * ***  *   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)
{
*     *    * *     * ** ** count=0;
* * **    * *     ** * *  != 0)
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* *************  **    **  *
*  * *** ** * *  ****   ** ** * count;
}

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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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    *    *  ***** * *  * 
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}

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;
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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'