c - Reading integers with commas between them -

i assumed using strtok best because of formatting of input. i've run few problems when trying detect errors:

an example of line program read:

 .data 123,456,89   .data     12,   34,   53   ,   64 

these ok.

my problem when input incorrect, example:

 .data 200 4000 // no comma speration  .data 1, ,3 // ,3 should error  .data 4, // , should error  .data 12.2 // .2 should error  , on 

my code (size buffer size = 30, valid_num goes through token see if chars numbers), idea first check validity of tokens , add them buffer, if numbers valid, add numbers data base:

 while((sptr = strtok(null, ", \t\n")) != null){ //this after reading using strtok before.     if(i < size && valid_num(sptr)){ //buffer not full , token contains numbers         temp_num = atoi(sptr);         if(temp_num >= min_val && temp_num <= max_val){ //number within required size             buffer[i] = temp_num; /*fill buffer*/             i++;         }         else{             fprintf(stderr, "(%d) error: %d out of bounds. valid numbers between %d , %d\n", line_count, temp_num, min_val, max_val);         }     }     else{         fprintf(stderr, "(%d) error: %s not valid number\n",line_count, sptr);     }     tok_count++; }  if(i == tok_count){ //if tokens read correctly, add data database.     dc += add_data(buffer, tok_count, dc, data_table); } else{     if(sptr != null){     fprintf(stderr, "(%d) error: %s not digit, .data can used integers\n", line_count, sptr);     }  } 

should try same sscanf, though length of input unknown?

how can enforce pattern? number - comma - number ...

perhaps using few different strtok inside loop?

there many ways parse line.

op's temp_num = atoi(sptr); not detect overflow 1) overflow atoi() undefined , 2) there no error return value.

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i believe below cope hostile input. not use strtok(), strtol() find non-numeric input.

making use of helper functions provides clarity of each step.

#include <ctype.h> #include <errno.h> #include <stdlib.h>  void consume_whitespace(char **input) {   while (isspace((unsigned char ) **input))     (*input)++; }  int parse_int(char **input, int *dest) {   char *endptr;   errno = 0;   long y = strtol(*input, &endptr, 10);   if (*input == endptr) return -1; // no conversion   if (errno) return -1;  // overflow   #if long_min < int_min || long_max > int_max     if (y < int_min || y > int_max) return -1;  // overflow   #endif   *input = endptr;   *dest = (int) y;   return 0; }  int parse_data_line(char *input, const char *prefix, int *dest, int n) {   size_t prefix_length = strlen(prefix);   if (memcmp(input, prefix, prefix_length)) return -1;   input += prefix_length;    int i;   (i = 0; < n; i++) {     consume_whitespace(&input);     if (*input == '\0') break;     if (i > 0 && *input++ != ',') return -1;     if (parse_int(&input, &dest[i])) return -1;   }   consume_whitespace(&input);   if (*input) return -1;  // text   return i; } 

example usage

#define size 30 int main() {   int numbers[size];   char *input = foo();   int count = parse_data_line(input, ".data", numbers, size);   if (count < 0) puts("fail");   else bar(numbers, count); }