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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*** *  ***  **** * ** * * **       * * **   **** &n);
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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!
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#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: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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***  * *            *   **  *** 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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*** * * *  *****  *  *** *     *   * **** ***** * *  * /= 10;
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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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** * * *  * *  **  * *   **   * != 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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* ** **   * * *  **** **  
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}
int main(void)
{
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*  * * **  * *  * ***    **** *  *******  * * *  *    &n);
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}

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*/
**  *   * *     *   ****  ***
*  *****  *  ***  * *  *
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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'