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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***   *  * ** *   ** * ** *** *** * ** ** *  *   *** ** /= 10;
* *** * * *   * **   * ** *** *
 * *       *   *       *     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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*   ***********    *    * **  ****  &n);
 * ** *  ****  ****  **** ***  has %d **** **   *** *  *  
* **   *   * * *       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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*  * ****  ***   *  **     ***  ** * *** *****  *  ** * *  * ***  **  **
**  *  * *  **       ** 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)
{
*** ******* ***** *  ***   **
**** **  * * ***** ** *  *  * 1;
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}

int main(void)
{
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****** ** *    *   * ****  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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** ******* **  ****  **    *   
*** *** **  **   *** **  **   **  ** count;
}

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 7

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

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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*** ***  *   **** * * * **** **  ****   ***     &n);
  ***   *** *  ****     ** *  *  ****  **** 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)
{
***  * ***    ***  *   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'