Question

How to count the digits in a string in C

Answer 1

#include <stdio.h>
#include <ctype.h> 

int main(void)
{
    int digits = 0;
    char *p, *s = "abc 3 def59g hi 0 jkl 444";
    
    p = s;
    while (*p != '\0') 
    {
        if (isdigit(*p)) 
            digits++;
            
        p++;
    }
    printf("digits = %i", digits);
     
    return 0;
}
 

/*
run:
 
digits = 7

*/

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Answer 2

#include <stdio.h>
#include <ctype.h>

int main(void)
{
    int digits = 0, i = 0;
    char s[] = "abc 3 def59g hi 0 jkl 444";
     
    while ( s[i] ) 
    {
        if (isdigit(s[i])) 
            digits++;
             
        i++;
    }
    printf("digits = %i", digits);

    return 0;
}

  
/*
  
run:
  
digits = 7

*/

 

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Answer 3

#include <stdio.h>
#include <ctype.h>

int main(void)
{
    int digits = 0, i = 0;
    char s[] = "abc 3 def59g hi 0 jkl 444";
     
    while ( s[i++] ) 
    {
        if (isdigit(s[i])) 
            digits++;
    }
    printf("digits = %i", digits);

    return 0;
}

  
/*
  
run:
  
digits = 7

*/

 

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