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

內容已隱藏
#include <stdio.h>
int num_digits(int n)
{
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    * **  **  *     ***   * * **   *** *       /= 10;
* * *** ** ***  **  ****  
 * *** * * **  **  * ***   *  *  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

內容已隱藏
#include <stdio.h>
int num_digits(int n)
{
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**     * *** * ** *  * **  *  ****** i;
}

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 3

內容已隱藏
#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

內容已隱藏
#include  * ** *** * * ***
#include ** **** ** * *
int is_prime(int n)
{
   **  * ** *    **   * divisor;
if (n<=1)
 *  * *  *** **** * false;
for (divisor   **    ** *  *   * 
**   ****  ** * *    *** * 
return true;
}
int main(void)
{
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* *   **** * **  **  **  * *  *   *  * * &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

內容已隱藏
#include **  *  *  * **   
int num_digits(int n)
{
*  *     ** * *  *     ******* **
**           ** ******    *** * 1;
*** *  *** *   **   
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**       **  * ** **  **** *  *  *   **
}

int main(void)
{
*** **** * **  * *    * n;
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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

內容已隱藏
#include <stdio.h>
int num_digits(int n)
{
 *    *** * ***  ** **  **** * count=0;
**  *  ** ******   ** *  **** != 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 7

內容已隱藏
#include <stdio.h>
int num_digits(int n)
{
 * **   **** **   *    *  ** cnt=0;
**   ** *  *  *  *** ***** ** != 0)
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* ***  *   *   ***    *** *    *  **   * **  *  * **** * /= 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

內容已隱藏
#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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 **  ****** * **  *   ***** **   *** has %d  **  *** *   ** ** * *   ** 
*      **  ***   *** * *    ***  0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 9

內容已隱藏
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

內容已隱藏
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'