Question

Write the following function without using the C++ string class or any functions in the standard library, including strlen(). You may use pointers, pointer arithmetic or array notation. Write the function lastNotIn(). The function has two parameters (str1, str2), both pointers to the first character in a C-style string. You should be able to use literals for each argument. The function searches through str1, trying to find a match for the last character NOT found in str2. Return the index of the last character in str1 that does NOT appear inside str2. Note that if all of the characters in str1 appear in str2, then return -1. Call the function like this: cout << lastNotIn("eieioh", "aeiou"); // prints 5 (the index of h) cout << lastNotIn("aaaiii", "aeiou"); // prints -1 (all inside s2)

Answer 1

Answer:

Following are the program to this question:

#include <iostream> //defining header file

using namespace std;

int lastNotIn(string str1, string str2) //defining method lastNotIn

{    

int s1_len=0, i, loc=0, j=0; //defining integer variable

while(str1[s1_len] != '\0') //defining loop that checks str 1 length  

{

s1_len++; // increment length by 1  

}

for(i=s1_len-1;i>=0; i--) //reverse loop for str2

{

   while (str2[j] != '\0') //finding last index value

   {

   if (str1[i] == str2[j]) //comparing all character value

   {  

   loc=1; //assign value 1 in loc variable  

   break; //using break key  

   }

   else //else block

   {

   loc=0; //assign value 0 to loc variable

   }

   j++; //increment loop variable value by 1

   }

   if (loc == 0) //check condition value it is not found then

   {

   return i; //returns value of i

   }

}

  return -1; //return value -1

}

int main() //defining main method

{

  cout<<lastNotIn("eieioh", "aeiou")<<endl; //call method and print its value

  cout<<lastNotIn("aaaiii", "aeiou")<<endl;  //call method and print its value

  return 0;

}

Output:

5

2

Explanation:

In the above program, a method lastNotIn is defined, that accepts two string value "str1 and str2" in its parameter, inside the method four integer variable "s1_len, i, loc, and j" is declared, in which all the variable assign a value that is equal to 0.

• In the next line, a while loop is declared, that counts str1 value length, and another for loop is used, that reverse value of str2, inside the loop a conditional statement is used, in if the block it will match str1 and str2 value if value match it will assign 0 in loc variable. otherwise, it will go to else block.
• In this block it will assign 0 in loc variable and increment the j value by 1, outside the loop another if block is used, that check value of loc is equal to 0, if it is true, it will return i value.
• In the main method, we call the method two times, the first time, it will give value 5, and the second time, it will give 2.