#include <stdio.h>
#include <ctype.h>
#define STRSIZ 100
//Recursive Function to Extract Capital Letters from a String
//Forms a string containing all the capital letters found in the input parameter str.
// caps has sufficient space to store all caps in str plus the null
char*
find_caps (char caps[], //output - string of all caps found in str
const char str[]) //input - string from which to extract caps
{
char restcaps[STRSIZ]; //caps from reststr (rest of string)
if (str[0] == '\0')
caps[0] = '\0'; //no letters in str means no caps in str
else
if (isupper(str[0]))
sprintf(caps, "%c%s", str[0], find_caps(restcaps, &str[1]));
else
find_caps(caps, &str[1]);
return (caps);
}
int
main (void) {
char sentence [] = "I Left My Heart in San Francisco";
char capital_letters[STRSIZ];
find_caps (capital_letters, sentence);
printf ("%s\n", capital_letters);
return (0);
}
