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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***  ** ****  **** ** *   
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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 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 ********  *  *  
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int num_digits(int n)
{
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{
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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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*****  * *****  *    * * 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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}

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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}

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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***   * **  *  * ** * ** *
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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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*   *    * ***  * *    **   != 0)
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**   **  *  *    **** ** ** ** count;
}
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 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);
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*****  *  ** *    ** * ** 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'