#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void fun(char *src, char *dest)
{
    int i = 0, j = 0;
    for (i = 1; i < strlen(src); i += 2)
    {
        if (src[i]%2) dest[j++] = src[i];
    }
    dest[j] = 0;
}
int main(void)
{
    char *p = "hello world!\n";
    char *str = (char *)malloc(strlen(p)/2 + 1);
    fun(p, str);
    printf("str :%s\n", str);
    free(str);
}