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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}

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)
{
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if (n<=1)
*** ** ***     *** false;
for (divisor * *** **   *        * *** 
* * **** *  * *    *    *  
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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***** *  *** **    *  *   ***  *  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)
* * ** *  **** ** **  *   
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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)
{
*  * ** *** *** * ***      ** cnt=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 8

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