string manipulation

[Haidar you]

hey guys i need help with my code ; well I am required to write a program that uses getline to read a string, counts the number of occurrences of the substring “is” in this string, and replaces all occurrences of “is” by “at” . I've written the code but there seems to be an error in replacing "is" and "it".

  #include <iostream>
#include <string>
using namespace std;

int main() {

	int length=0, position=0;
	int counter=1;
	
	string statement ;
	string string1 = " is ";
	string string2 = " at ";
	
	cout << " Enter a statement : " << endl;
	getline(cin , statement);

	length = statement.length();
	position = statement.find(string1);

	while ( position != string::npos ) {
		for ( int i = 0 ; i < string2.length() ; i++) {
		
			statement.replace(position, string1.length() , string2 ); 
		}
		counter++;
		
		
			
		position = statement.find( string1 , position + string1.length() );
		
	}
	

	cout << "The number of occurance of \"is\" is :" << counter << endl;
	
	cout << "The new statement after being altered is : " << statement << endl;

	system ("pause");
	
	return 0;
}

[vlad from moscow]

First of all why was counter initialized by 1?

The main loop is simple

size_t counter = 0;
std::string::size_type n = 0;

while ( ( n = statement.find( string1, n ) ) != std::string::npos )
{
	statement.replace( n, string1.size(), string2 );
	counter++;
}

[Haidar you]

thnx it worked well, but is it possible that you could tell where the my code failed; would appreciate it.

[vlad from moscow]

Except that your code is silly, for example what does this loop do? }

		for ( int i = 0 ; i < string2.length() ; i++) {
		
			statement.replace(position, string1.length() , string2 ); 

}

I see the only reason that you skip the trailing balnk. For example for this statement

" is is "

your code will not work because it will not find the second

" is "