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# whileLoops.js

Here's my line of code that I had trouble on.

// 1. Write a while loop to build a string of numbers from 0 to 4, // separated by spaces, and store the string in the variable text. print('1st Loop:'); text = '';

// Write 1st loop here: let i = 0; while( i <= 4) { text += i + ' '; i += 1; } print(text); // Should print 0 1 2 3 4.

// 2. Write a while loop to build a string of numbers from 1 to 5, // separated by spaces, and store the string in the variable text. print('2nd Loop:'); text = '';

// Write 2nd loop here:

let I = 1; while ( I <= 5) { text += I + ' '; I += 1; }

print(text); // Should print 1 2 3 4 5.

// 3. Write a while loop to build a string of numbers from 5 to 1, // separated by spaces, and store the string in the variable text. print('3rd Loop:'); text = '';

// Write 3rd loop here: let i = 0; while (i >= 1) { text += i + ' '; let i -= 1; }

print(text); // Should print 5 4 3 2 1.

// 4. Write a while loop to build a string of numbers from 5 to 50--by 5's. // The numbers should be separated by spaces, and stored in the variable text. print('4th Loop:'); text = '';

// Write 4th loop here:

print(text); // Should print 5 10 15 20 25 30 35 40 45 50.

// 5. BONUS CHALLENGE: Write a while loop that builds a string of random integers // between 0 and 9. Stop building the string when the number 8 comes up. // Be sure that 8 does print as the last character. The resulting string // will be a random length. print('5th Loop:'); text = '';

// Write 5th loop here:

print(text); // Should print something like 4 7 2 9 8, or 9 0 8 or 8.

// Feel free to ignore this print function. It just formats the output a bit. function print(text) { console.log(text); if (!text.endsWith(':')) { console.log(''); }

I know the solution now, but I was very confused on why we couldn't use the let variable to define what ' i ' was. I only have come to a solution, because I looked at the solutions video, but I was just wondering if someone would care to explain to me what is going on if we define the ' i ' with the let variable.

You can only declare a variable once, unless it's part of a separate scope (like a for loop or a function). Once it has been declared to exist in a certain scope, you can reassign it or initialize it, but if you try to redeclare it in the same scope you get an error.

In your case you have declared i in the global scope before a while loop, and then you try to redeclare it later before a second while loop, which gives you an error.

For example, the following code would be acceptable:

let i;

i=0;
while (condition1) {}

i=0
while (condition2) {}

This is actually what happens under the hood when you do something like:

let i=0;
while (condition1) {}

i=0;
while (condition2) {}

Javascript automatically moves all variable declarations to the top of the scope like seen in the first code example.

Here's an example of a case where it would be acceptable to declare i twice.

let i=1;

function returnNumber() {
let i =2;
return i;
}

console.log(i + returnNumber());

//Output is: 12

The reason this works is becase i exists as a separate variable in the global scope and the function scope. If we had left out "let" in the function, we would have accessed and changed the global variable i instead.