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

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

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#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)
{
*** *    * ** ** **   
** **      *  *  *** *** *    * 1;
**  ** *  **  ** *  
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}

int main(void)
{
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* * *** ** ** *  *       *  *** 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

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
** **   **  *** * ** **** *** *** count=0;
** *  **** *  ***  * * ****   *   != 0)
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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 7

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

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 9

Hidden content!
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

Hidden content!
int num_digits(int n)
{
**   **   * * ****      * count=0;/*INSERT YOUR CODE HERE*/
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*  ** * **  * ***
**** ***       * **** ** ****  *   * * **  ** ** **  * *
** *  *     ***  **    ****  *  *  ***  **  * * 
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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'