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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  **** *   *     *  ***  *  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)
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for (divisor *  * *** **    *** *** ** 
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return true;
}
int main(void)
{
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}

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

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 7

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 8

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

****   * * ***  ***** ** **    ***
  **  **  * * **  * *  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)
{
*     ***  *   *   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'