#include <limits.h>
#include <string.h>
#include <stdlib.h>
#include <stdexcept>
#include <stdio.h>

const int _undef_int = INT_MIN;

struct scan_context_t {
  const char* text;
  size_t pos;
};

void scan_spaces(scan_context_t* context) {
  const char* text = context->text;
  size_t p = context->pos;
  while (text[p] == ' ') p++;
  context->pos = p;
}

bool try_scan_tok(scan_context_t* context, const char tok[]) {
  size_t tl = strlen(tok);
  if (strncmp(context->text + context->pos, tok, tl) != 0)
    return false;
  context->pos += tl;
  return true;
}

void scan_tok(scan_context_t* context, const char tok[]) {
  if (!try_scan_tok(context, tok))
    throw std::runtime_error("Syntax error.");
}

inline bool is_digit(char c) {
  return ('0' <= c) && (c <= '9');
}

int scan_int(scan_context_t* context) {
  if (!is_digit(context->text[context->pos]))
    throw std::runtime_error("Syntax error.");
  char* end;
  int result = strtol(context->text + context->pos, &end, /*base:*/10);
  context->pos = end - context->text;
  return result;
}

void insert_records(int count, int price);

void insert_records_from_text(const char text[]) {
  scan_context_t sc = {text, /*pos:*/0};

  // пропускаем не-цифры
  for (;;) {
    if ((text[sc.pos] == '\0') || is_digit(text[sc.pos])) break;
    sc.pos++;
  }

  int count, price_1;
  int n = scan_int(&sc);
  scan_spaces(&sc);
  if (try_scan_tok(&sc, "*")) {
    count = n;
    scan_spaces(&sc);
    price_1 = scan_int(&sc);
    scan_spaces(&sc);
  } else {
    count = 1;
    price_1 = n;
  }

  int price_2 = _undef_int;
  if (try_scan_tok(&sc, "+")) {
    scan_spaces(&sc);
    price_2 = scan_int(&sc);
    scan_spaces(&sc);
  }

  scan_tok(&sc, "руб");

  printf("Parsed text '%s'.\n", text);
  insert_records(count, price_1);
  if (price_2 != _undef_int)
    insert_records(1, price_2);
  printf("\n");
}

void insert_records(int count, int price) {
  printf("Inserting %i record(s) with price %i.\n", count, price);
}

int main() {
  insert_records_from_text("... 200 руб...");
  insert_records_from_text("... 4*300 руб....");
  insert_records_from_text(".... 4*200+300 руб....");
  insert_records_from_text("...100+200 руб....");
  return 0;
}

Parsed text '... 200 руб...'.
Inserting 1 record(s) with price 200.

Parsed text '... 4*300 руб....'.
Inserting 4 record(s) with price 300.

Parsed text '.... 4*200+300 руб....'.
Inserting 4 record(s) with price 200.
Inserting 1 record(s) with price 300.

Parsed text '...100+200 руб....'.
Inserting 1 record(s) with price 100.
Inserting 1 record(s) with price 200.