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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***** * ****** ****   **  **     ** ** **  ** *** *** ***** * 
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* **   * **   * ** * ****
*   *  * **     ***     * ****  * count;
}

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

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);
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** * * * **  ** ** ** 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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**   ****  ***** * 
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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);
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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;
  *** *     *  **  ** 
* ** *  * * *** *        * 
* *  *  ****   **** **   *   *   *
}

int main(void)
{
* * *    * ** ***   ** n;
** ***    **  ** *    *  * *  ** **  * ***  &n);
* * * ***   ** ** ***  **  * ** ** * has %d    ** **     * **  * *
* *** *** * * ** * ******   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)
{
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* *     *   ***  * *** * **  * ***** *  != 0)
   ***   * ** *    *   *  *
    **  **  ** * *   *  *  *         *** ***  *   *
     *** *  *** ** ** * * *****  ** **  * *  *  /= 10;
***   * *         ****** 
* * ***** **** *** ***   **  *   * 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 7

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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*   **** ** *****  ** **  ** *  cnt;
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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)
{
** **  * **   **      *        count=0;
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** *  ******** * * * *** ***  *   *    != 0)
**  ***  ****   * * **  * *  
* **   * * *  **** *    *****  ** *** ****** *   *   * 
  *** **  ****   *    * ***  ** * ** *  * **   * *  ** ** * ++;
**  **  *  ***  **   *  *  ***
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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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** ***  **   *   * * ***  * *  *** * ******   * **  *
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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

內容已隱藏
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'