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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}

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 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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}

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)
{
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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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*   *   *   *** ***       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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  * *   ****** ***  ** *  **
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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 7

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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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****  *  ***  *    *   * != 0)
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****   *    **** ** ***** **  **    **  **   * ** * ** *  * ***
**   * ****   * ***      * * *     ** **  *   *  * ++;
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***   **       ****  * **** *   * * count;
}
int main(void)
{
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* ** *      * * * ***** *** *  ***       ** * * *    &n);
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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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*    *    **  * ** **** * *  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*/
 *  ******* *  *   * ***     ***
****** *   *  * ***  
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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'