substr.c

#include <stdio.h>

// Example of code in C to get substrings
char *substr(char *dest, char *src, int start, int end)
{
  char *start_address = dest;

  for (src = src + start; *src && end > 0; dest++, src++, end--) {
    *dest = *src;
  }

  *dest = '\0';
  return start_address;
}

int main(void)
{
  char buff[32] = "Dados anteriores";
  char test[] = "Eu sou um teste";
  
  puts( substr(buff, test, 3, 3) ); // "sou"
  puts( substr(buff, test, 10, 30) ); // "teste"
  
  return 0;
}