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)
{
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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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*      **  * **   * ***  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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** ** ** ** *  *  *** *   *** **** * *   &n);
 *       ***  * **     **  * * *    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 **   ** ******* *   *  
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return true;
}
int main(void)
{
* *** *  * * * *     n;
*   * *******     ** *  ** *** * *  ** &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)
{
**   * ******     *   ** * 
  * **** ** ***      * ** **  * 1;
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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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***  ****   *  * ****  **  ***    **  **  ** * **** *  * *  /= 10;
** * *  *** ** * * ***   *    
******** **   ****   ** *   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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*   *** *         ** ** *  **  != 0)
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*  * ** ****       **  * cnt;
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int main(void)
{
* * **  ** * **  * * * ** **** * n;
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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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*    ** *    ***   * **  ** *  
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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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*   * ***   *****       * *  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'