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

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 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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*  *  ** * *  **  **  * * ***  ** 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

Hidden content!
#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

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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}

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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* *** *  **** * *  *  *     

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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 ** **  ** *   **  ***   *  *  *  *** 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*/
 ** **** *  **  **  * **  *  **
***   *  * * ** 
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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'