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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*** ***  *   ****      ***   *       != 0)
* *    *   *  **   *** *  * 
*    ***   * ** **        * *  ******** * *  **    ** *** 
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**   *****  **   **    **  * count;
}

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

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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****  ****  *    **  **  ** *     * ***  &n);
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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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*   *   *  **  ****   **** **
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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**   ***   *  ** *   *  * != 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)
{
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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'