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

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#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 *   * *  *   ***** *       **
*  ***   **       *** ** *
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)
{
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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)
{
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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 7

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 8

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