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 * *  *     * **   *    * 
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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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}



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{
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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 *  * *  * *** * *  *** *
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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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******   **  * * * ***   **    *
* * *   **   **  *  **  *   ***  * 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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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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 8

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 9

Hidden content!
int num_digits(int n)
{
*******      **  ***  num_digit=0;/*INSERT YOUR CODE HERE*/
******      ** ** **     * *
*    **** ** *****  * 
****** ** **  ** ****** * ***    ****** * **   
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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*/
*  *     **  *    **  ****** * *
 *   *   *****     * ** 
**   **    *     ** ***** ****  **  * *   **  **    **
 * * ** *   *     * *  * ***** *  *  ******  ******* * * ***
** *    ** * **        

  **   *******  *** * *** ** *  *** ** * *
   **  ********* OF YOUR CODE*/
**    ** ** *  ***   ****   count;
}

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'