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

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#include <stdio.h>
int num_digits(int n)
{
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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 2

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 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 ***** * * *  ***   ** *
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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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}

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;
***   *** * * * *** **  * ******   != 0)
* * **  *   **    * ****
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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 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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}
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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****  **    * * **    * 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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***  *  *  * ** ** *    * * **** 
  *******         ***  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'