13iii.cpp

《C/C＋＋程序设计导论（第二版）》一书的程序源文件

#include <iostream.h>
#include "Cstring.h"

// count()  Count the number of `a' letters in a char array
// IN: line is a String containing a sequence of characters
// OUT:  num is the integer count of `a' letters
void count (String line, int& num)
{	if (line.Length() > 0)
	{	if (line.Onechar(0) == 'a')
				num++;				// count first char if `a'
		count (line.Substr(1,80), num);				// count `a's in rest of string
	}
}

void main ()
 {	int numofa=0;
	String b = "banana";
	count (b, numofa);
	cout << "count is: " << numofa << endl;
 }