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

int main(void)
{
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* ** **  ** *** *   * *  ***** *** **  ** * has %d   **   **    *  * *** 
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}

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)
{
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if (n<=1)
* * **     *  *   false;
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)
{
*     *    ** * *  *   **  **  
* ** ***  *** ****    ** *   1;
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}

int main(void)
{
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*** *    ****** *** * * ****  *   ** &n);
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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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* ******* *  * *****    * *  *    * *** **** * **
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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 7

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

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

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'