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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}

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 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

Hidden content!
#include *   * **  * ** * 
#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: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);
**  * * ****  ****    (is_prime(n)) * **   ***** **    *  ** ** ** *** ****   **   *   ** function return 1
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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    *** *  ** * *    *******  *
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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)
***  ****** ** * ***  *   * 
*    ***  *   ****   *   ****** ** *  * * * ****  *  * 
*  *  *    * *     * *     *   **** ***   * * * ** **     *     /= 10;
   ** ****   ***  ***   
*  ***** * *** ** * *    *  ***** count;
}

int main(void)
{
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*  *      * *   **  **   ****  **** **   ** * &n);
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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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*  *  ** ** **   *     *   *  * ** *****   ****    *  ***  *
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***   * **** * * *** **   *    *  *  cnt;
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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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** *** **   * **  **** **   *** *  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 9

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

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