Question regarding assigned values for c++ program

[cookiemnstr510]

Hello all,
This is my first post.
I am taking an online summer beginning c++ course.
We are using C++ programming from problem analysis to program design 7th edition by malik.
I understand some basic things with c++ such as how to write a program that prompts users to enter test score data and obtain the average of these test scores. I have learned about different data types, assignment statements, how to assign variables etc. some pretty basic things.
I just learned about the get, putback, peek etc functions.
There is an exercise at the end of chapter 3 (which I just read) that I do not understand what it is asking and I am hoping someone can shed some light on it or at least have a discussion with me and point me in the right direction.

Heres the assignment:
Suppose num1 and num2 are int variables and symbol is a char variable. Consider the following input: (2)
47 18 * 28 $
what value (if any) is assigned to num1,num2 and symbol after each of the following statements executes? (use the same input for each statement.)
a. cin>>num1>>symbol>>num2;
b. cin>>symbol>>num1>>num2;
c. cin>>num1;
cin.get(symbol);
cin>>num2;
d. cin>>num1>>num2;
cin.get(symbol);
e. cin.get(symbol);
cin>>num1>>num2;


That is the assignment
What I get out of what it is asking:
First of all I understand that the input is 5 things, some are int values and some are symbols (the * and $)
for a: so num1's value would be 47 and then the program has an input failure because the next thing that is entered is not a symbol? is this the correct way to think about it?
for b: the program fails right off the bat because the first thing we input is not a symbol it is a number?
for c: num1=47
symbol= (blank)
num2=18?
really not sure about this one..
for d: num1=47
num2=18
symbol=*
for e: program fails because first character the 4 is not a symbol?

anyway if someone could steer me in the right direction that would be great.
Thanks and let me know if the formatting of my question is correct or if i could write more/less to make it clear since I know nothing about programming language as I am just starting this course.

Cheers,

William

[2kaud]

a: so num1's value would be 47 and then the program has an input failure because the next thing that is entered is not a symbol? is this the correct way to think about it?

num1 is 47 but the next input is 1 which would be read to symbol as 1 is a char. Then what happens?

for b: the program fails right off the bat because the first thing we input is not a symbol it is a number?

No - for the same reasoning as a).

for c: num1=47 symbol= (blank) num2=18?

Spot on! >>num1 extracts the first 47 to num1 then .get() reads the following space then >>num2 extracts the 18.

for d: num1=47 num2=18 symbol=*

num1 is 47, num2 is 18 but symbol is <space> as the .get() gets the character following the last extraction which was 18 and so gets a <space>

for e: program fails because first character the 4 is not a symbol?

No, because for a) the initial 4 is a character which will be read into symbol.

[cookiemnstr510]

I believe I see what you are saying, will work on it and get back to you with my results
Thank you very much

[cookiemnstr510]

Ok so here is what I have concluded
for the same inputs like stated earlier which are:
47 18 * 28 $
A) cin>>num1>>symbol>>num2;

num1=47
symbol=1
num2=8
B) cin>>symbol>>num1>>num2;

symbol=4
num1=7
num2=18
C) cin>>num1;
cin.get(symbol);
cin>>num2;

num1=47
symbol= ' '
num2=18
D) cin>>num1>>num2;
cin.get(symbol);

num1=47
num2=18
symbol= ' '
E) cin.get(symbol);
cin>>num1>>num2;

symbol=4
num1=7
num2-18

How does this look?

Thanks

[2kaud]

a)

b)

c)

d)

e)

Congrats!

[cookiemnstr510]

Thank you very much!
very helpful!!!

[2kaud]

However, usually in programming it is the other way round. Given an input format how would you read it into a program?

Say the input was
1) 12 34 +
2) 12+i1
3) +2+4+5
4) 34 56 23 * + 11

What statements/definitions would be needed to read these into a program?

[cookiemnstr510]

Here is what I think:
int num;
char symbol;

1) cin>>num>>num>>symbol;
2) cin>>num;
cin.get(symbol);
cin.get(symbol);
cin.get(num);
3) cin.get(symbol);
cin.get(num);
cin.get(symbol);
cin.get(num);
cin.get(symbol);
cin.get(num);
4) cin>>num>>num>>num>>symbol>>symbol>>num;

My initial thought was to define 9 numbers: num1=12, num2=34, num3=1, num4=2, num5=4, num6=5, num7=56, num8=23, num9=11 The reason i thought to do this is because when i looked through what the input you gave me I saw 9 different numbers.
In addition to this I saw 3 different symbols: symbol1=+, symbol2=i, symbol3=*.
So 1 could be:
cin>>num1>>num2>>symbol1;

Which way would be correct? Is it necessary to assign all different numbers/symbols to different locations (i.e. num1, num2,...etc.) or is it sufficient to assign num as an int data type and leave it at that?

[2kaud]

1)

2) cin.get(num);

.get() can only be used to extract character(s). To extract a number use >>

3) Same as for 2)

4)

So 1 could be:
cin>>num1>>num2>>symbol1;

This would usually be what would be used so that the contents of both num1 and num2 are available in the program. If

cin >>num>>num>>symbol;

is used, then num would be 34 and the 12 extracted from the stream would be 'lost'.

Do you have access to a c++ compiler so that you can try these in actual code?

[AvDav]

There are lots of online console-based compilers available on the internet.
One of them is www.cpp.sh, you don't even need to dig into the procedures of the installation or such.

[cookiemnstr510]

good afternoon!
Yes I have x-code installed on my computer and have been trying things out