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

Hidden content!
#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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******** **** ** ******  *       **   * **    &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

Hidden content!
#include  *** **** *  
int num_digits(int n)
{
** **     *    * *     *** **** 
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**  ***     *** *      
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*     *  **** ***   ** * *   * *  * 
}

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

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)
{
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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)
{
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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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 *    *   *  *      * ***  *  ***    ***   ** **  ***   *
* *  ** *  **   *  **

 *** *     * ****  ** *   * ***** * **  *
**   ****   ***  **  *  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'