Question

Does a do-while loop check a value before or after it has been incremented? I can’t seem to make this do-while loop escape, and can’t determine if that is the mistake I am making. The point of this loop is to take input from the user and when they hit ‘X’, I want the loop to end. Am I using the wrong type of loop, or perhaps an incorrect statement?

int i = 0, 
inputCount = 0;
char letter = 'a';
String[] coefficient = new String[MAX_LENGTH];  
do{ 
    System.out.print("What is " + letter +"? ");
    coefficient[i] = keyboard.nextLine();
    i++;
    letter++;
    inputCount++;           
}while(coefficient[i] != "X");

Answer 1

You’re incrementing i between coefficient[i] = keyboard.nextLine(); and while(coefficient[i] != "X");, so in the while check coefficient[i] is null, also use .equals to compare strings.

int i = 0, 
inputCount = 0;
char letter = 'a';
String[] coefficient = new String[MAX_LENGTH];  
do{ 
    System.out.print("What is " + letter +"? ");
    coefficient[i] = keyboard.nextLine();
    i++;
    letter++;
    inputCount++;           
}while(!coefficient[i-1].equals("X"));