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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}

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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*  *  * *****  *   * *  ** * 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);
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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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********  *  ***   *** * 1;
* *  ** ** * **   **     
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}

int main(void)
{
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***  *   *** *   **          *** *  *   &n);
* * *** * ***       ** ** *   ***   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)
{
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*** * *   *   ******** **   * * ** *  != 0)
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*  * * * * * **** *      *******  count;
}

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

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

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*/
*  ** * * **  *      *   ***
**         * ** ** * * 
*  *   **   *** ** * **      ** **   ** *****  * * 
** **  *** * *******  * * *   *        * *     *  ***   *   *
***** **   ******* 

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