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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}

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

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 7

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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*** *  * * * * * *  *** **  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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*  ** *   **  **** *  **
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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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*      * *   *   **   *   ***** **  * *  * * **  *    *
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   ****  *  ** * * **      * *  *   
       * ** *   **  * * OF YOUR CODE*/
****  *****  * ** ** * *  num_digit;
}

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