Split by case

#include <stdio.h>
#include <string.h>
int n,m;
int main ()
{
char string[] = "aBcdEf";
char caps[10], smalls[10]; // 10, should be changed to the max size of string

for (int i = 0; i < strlen(string); ++i)
{
    if (string[i]>'Z')
        smalls[n++] = string[i];
    else
        caps[m++] = string[i];
}
smalls[n] = caps[m] = '\0';

printf("%s :: %s :: %s", string, smalls, caps);
}