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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}

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)
      ***  * * * false;
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)
{
*** *    ** *** * * ***    
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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;
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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 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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*** ***   ****     * * * *** *  *** 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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**    **       ***   * * * ** *      * * ***   *  * *  ++;
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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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** ****   * * *   *** *  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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 *** * * * *** *  *** 

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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'