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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**  **   *** * **     *** **  *****  * * 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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}

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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* *      ****   ** ** * (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)
{
 *       *   ** * *   **  * *
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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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***** *   **   * ** *    *  *   * *****  *** &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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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 8

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