What's wrong here? (Says b was not declared in this scope)

Question

#include <iostream>
using namespace std;

int main()
{
for (int a = 0; a < 10; a++) {
cout << a << endl;

while(a < 10)
int b;
cin >> b >>endl;
cout<<b << "not enough"<<endl;
}
return 0;
}

Answer 1

@Justme following people

-helps you keep track of other users

-to easily access their profile codes posts

I did it to win challenges, helps keep track on who the stronger challengers are, for each language.

Like @Peter (C#) and the #1 Nikolay (most of them?)

Answer 2

First thing
The while loop never ends, and so the for loop never increments(infinite loop)
Second thing
You can declare a variable only once. Since you have placed
int b;
in the while loop it is declared every time. This also causes an error.

Hope this helps.

Answer 3

@Justme, every programmer begins with an error.

Answer 4

And remove int b; from the while loop.
#include <iostream>
using namespace std;

int main()
{
int b;
for (int a = 0; a < 10; a++) {
cout << a << endl;

while(a < 10)
cin >> b >>endl;
cout<<b << "not enough"<<endl;
}
return 0;
}
//This is still an infinite loop.

Answer 5

b is declared in the scope of the while loop. You forgot brackets in the while loop so it's only reading the one statement: "int b;".

I ASSUME this is what you are trying to do:

for (int a = 0; a < 10; a++) {
cout << a << endl;

while(a < 10)
{
int b;
cin >> b >>endl;
cout<<b << "not enough"<<endl;
}
}
Note* this is an infinite loop.

Answer 6

I have not nest loops like that before.
u
oh it needs another } at the end before return 0.

Answer 7

True I was trying to make an infinite loop thank's btw.

Answer 8

Amrit thank's didn't knew that actually if I put int b; indide while loop it was declared continiously :/ (my mistake). 👌

Answer 9

@manual That would prevent it from being infinite, yes. However, the for loop wouldn't continue when the while loop ends.

Answer 10

yes becouse if you put ++a you are adding a value (+1) before the action so a actually reach 10 (i think)

Answer 11

@manual
Yeah, I don't think endl does anything with cin, so you could actually be right about that.

Also, I recommend never actually changing the variable that was created by a for loop, inside the loop. That can cause huge un-needed confusion in real projects. It's considered good practice to never do it. That's what the incrementation of the for loop is for.

@Justme
Following people lets you see what that person does on the "activity" feed. I guess so you can see more posts or codes they have done.

Answer 12

@Justme
The code you wrote was fine if you follow what @amrit said about declaring things outside loops (maybe also remove the endl with the cin). I'm talking about when manual asked about incrementing a.

Ex/
for(int i = 0; i < 100; i++)
{
++i;
// don't change this variable in the loop
// it will get confusingly unnecessary
}

I could have just done:
for(int i = 0; i < 100; i+=2)
{

}

Answer 13

does endline do anything for cin?

what does b do in this code?

Answer 14

actually don't know gonna check

Answer 15

I put it to dont have the text all together

Answer 16

You're welcome

Answer 17

What is the use of following people?

Answer 18

@ Rrestoring faith so should I use instead while...do loop? (just learn that)

Answer 19

aaa got it thank's

Answer 20

Would adding ++a inside the loop end the while loop?