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

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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***    *** * *   **** (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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**** ***    ** ****  ***** 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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***  *** *  * * **  * *  ****     ***   **  *******  /= 10;
**   *     *** *     ****  *
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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 7

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 8

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