c - Count how many integer values separated by spaces are in a given string -

i want make function that, given character string containing (unsigned) integer values separated spaces, gives me number of values in string:

int conta_coords(char *args) {   char *pal;   int k=0;   pal = strtok (args," ");   while (pal != null)   {       k++;       pal =strtok (null," ");   }   return k; } 

this function won't give me right number. can me?

in way won't give correct number? here's code embedded sscce (short, self-contained, correct example).

#include <string.h> #include <stdio.h>  extern int conta_coords(char *str);  int conta_coords(char *args) {   char *pal;   int k=0;   pal = strtok (args," ");   while (pal != null)   {   k++;       pal =strtok (null," ");   }   return k; }  int main(void) {     char data[] = "1 23 456 7890 12345";     printf("data: %s\n", data);     printf("number: %d\n", conta_coords(data));     printf("data split: %s\n", data);     return 0; } 

output:

$ ./cntnum data: 1 23 456 7890 12345 number: 5 data split: 1 $  

that looks correct me. note, though, original string has been chopped pieces. also, if had passed read-only string (string literal), might have gotten different results, because strtok() modifies data works on, string literals aren't modifiable (and may core dump out of trying modify it). example:

    printf("number: %d\n", conta_coords("   1     23    45   67    99    ")); 

this gives me 'bus error' (and give core dump if weren't disabled).

here's alternative implementation works on constant strings not modifying searched string @ all, using much-underrated c89 standard functions strspn() , strcspn():

#include <string.h> #include <stdio.h>  extern int conta_coords(const char *str);  int conta_coords(const char *str) {     const char  digits[] = "0123456789";     const char *ptr = str;     int   k = 0;     int   n = strcspn(ptr, digits);     while (ptr[n] != '\0')     {         ptr += n;         n = strspn(ptr, digits);         if (n > 0)             k++;         ptr += n;         n = strcspn(ptr, digits);     }     return k; }  int main(void) {     char data[] = "1 23 456 7890 12345";     printf("data: %s\n", data);     printf("number: %d\n", conta_coords(data));     printf("data unsplit: %s\n", data);     printf("number: %d\n", conta_coords("   1     23    45   67    99    "));     return 0; } 

output:

data: 1 23 456 7890 12345 number: 5 data unsplit: 1 23 456 7890 12345 number: 5 

note 1 legitimate criticism of not demand integers separated blanks (so more accurate characterization of 'count how many sequences of 1 or more contiguous digits (separated 1 or more non-digits) appear in given string'). original code can criticized on similar grounds: counts number of sequences of consecutive non-blanks, separated 1 or more blanks, appear in given string. can refine implementation, wary of how deal erroneously formatted data , report problems.