What is wrong with this code....i am trying to swap two numbers? //

Question

1.00/5 (3 votes)

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i dont know what is wrong with this code ......values of x and y are something out of this world .....

What I have tried:

using namespace std;

int main()

{
int x,y,z,t;
cout<<"x=";
cin>>x;
cout<<"Y=";
cin>>y;
x=z;
y=t;
cout<<"after swaping";
cout<<"value of y"<<z<<endl;
cout<<"value of x"<<t<<endl;

return 0;}

Posted 20-Dec-16 4:18am

Member 12914219

Updated 20-Dec-16 9:44am

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Comments

Michael_Davies 20-Dec-16 10:36am

Your not swapping anything, z & t are not initialised and you are overwriting the inputs in x & y with them.

Your also saying "value of x" then outputting t which is not initialised.

Initialise z & t to 1234 and 4321 and see what happens.

3 solutions

Solution 3

This is reversed,

C++

x=z;
y=t;

and should be replaced with

C++

z=x;
t=y;

but even with this correction, it is not a swap.

You should learn to use the debugger as soon as possible. Rather than guessing what your code is doing, It is time to see your code executing and ensuring that it does what you expect.

Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.

Posted 20-Dec-16 9:44am

Patrice T

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PeejayAdams · Accepted Answer · 2016-12-20T04:36:00

Solution 1

You set x to z but z is never initialised so will just have some random value, same with t (which you don't need anyway).

The correct logic would be z = x, x = y, y = z.

Posted 20-Dec-16 4:36am

PeejayAdams

Comments

Member 12914219 20-Dec-16 11:23am

are x=z and z=x differnt?

PeejayAdams 20-Dec-16 11:34am

Yes. Assignment goes to the left, so x = z would give x the value of z whereas z = x would give the value of x to z.

If we were assigning a value from a value rather than a variable we'd say, for example, "x = 2;" which effectively reads as "Let x have the value of 2." Similarly, when we say "x = z;" we are saying "Let x have the value currently assigned to z."

OriginalGriff · Accepted Answer · 2016-12-20T04:37:00

Um...You need to learn to use the debugger...

C++

int x,y,z,t;

Declares four variables, but does not give them any "sensible" value.

C++

cout<<"x=";
cin>>x;
cout<<"Y=";
cin>>y;

Reads a value into x and y

C++

x=z;
y=t;

Overwrites the values you read from the user with uninitialized values which contain no useful data.
That isn't a swap.
To swap, you don't need z, just t:

C++

t = x;
x = y;
y = t;