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



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{
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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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}

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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***      * **  * ***
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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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* ** *  *** ** ** * ***    ***   ****      ** **  * * *  *  /= 10;
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*      *   * ** *  *  ******    * count;
}

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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*    ****     ******   ** ** != 0)
** *  * *******  ** * 
* *   *** *    *  * * *     *** * *  **      **  **  ** /= 10;
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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 8

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

* **** ****  *  * * **  *  * * ***  * *
 ***   **    ** * *  ** 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'