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;
* ******* ***    **  *   
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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 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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**   *  *  ** *   *       *  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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*** *****  **  **  **   **      * * ****  &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)
{
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*  *  * * *    *  * 
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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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}

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)
{
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    *     *  **      **     *  *   != 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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* ** *****    *******  * 
** * * * * ***** *   *    * * **  != 0)
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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 9

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

int main(void)
{
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* * * ** ****      *    *    *    * *  ** * * * &n);
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*** ****   *     **   ** 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'