Remove vowels from a string

disemvowel.c

#include <stdio.h>
#include <string.h>

char *disemvowel(const char *str)
{
  char* result = malloc(strlen(str) + 1);
  char vowels[] = {'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'};
  int counter = 0;
  while(*(str) != '\0'){
    
    int allowed = 1;
    for(int i=0; i<10; i++){
      if(vowels[i] == *str){
        allowed = 0;
      }
    }
    
    if(allowed){
      result[counter++] = *str;
    }

    str++;
  }
  result[counter] = '\0';
  return result;
}