Why the result is onetwothree40 50 0 and not onetwothreethis is the end...40 50 0 ?

Question

5.00/5 (1 vote)

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C#

#include <stdio.h>

int main()
{
    int i=10,j=20,k=0;
    
    if(i=40)
      
      printf("One");
    if(j=50)
      
      printf("Two");
    if(k=60)
      
      printf("Three");
    if(k=0)
      
      printf("This is the end...");
    printf("%d %d %d\n",i,j,k);
}

What I have tried:

Why the result is onetwothree40 50 0 and not onetwothreethis is the end...40 50 0 ??

Posted 11-Oct-16 20:49pm

Stemm33

Updated 11-Oct-16 22:09pm

v3

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OriginalGriff 12-Oct-16 2:56am

Unfortunately, you have become the victim of a bug in the system, and your code is not readable. The admins are working on the problem, but it's a recalcitrant devil...
Basically, all your code after the first less than symbol has been assumed to be an HTML tag and removed, so we can't read anything after the "#include".
Please, edit your question (using the "Improve question" widget) and paste it again - this time using the "encode" or "code block" options in the paste pop-up on the right of your screen.

Suvendu Shekhar Giri 12-Oct-16 3:16am

try updating the question as sugested by @OriginalGriff

Stemm33 12-Oct-16 3:18am

I think i did

Suvendu Shekhar Giri 12-Oct-16 3:27am

Yes. It's perfect now.

Garth J Lancaster 12-Oct-16 3:32am

firstly, how do you compare values in 'c' vs assign values to variables .. ie, what is the difference between '=' and '==' and which do you think you should be using

Stemm33 12-Oct-16 4:00am

I know that in this simple code = change the value of my variables,but my actual question is why the three printf commands appear at the result and the printf("This is the end...") command doesnt appear?why program jump from the last if statement to the last printf command?

3 solutions

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Suvendu Shekhar Giri · Accepted Answer · 2016-10-11T21:36:00

Solution 1

That's because = is an assignment operator.
You need to use == for comparision.
Try-

C#

int main()
{
    int i=10,j=20,k=0;
    
    if(i==40)
      
      printf("One");
    if(j==50)
      
      printf("Two");
    if(k==60)
      
      printf("Three");
    if(k==0)      
      printf("This is the end...");

    printf("%d %d %d\n",i,j,k);
}

Hope, it helps :)

Posted 11-Oct-16 21:36pm

Suvendu Shekhar Giri

Updated 11-Oct-16 21:37pm

v2

Comments

Stemm33 12-Oct-16 3:47am

I agree that = is an assignment operator,but how the three printf commands appear at the result and not the printf("This is the end...") command?that's my actual question.

Suvendu Shekhar Giri 12-Oct-16 4:00am

Just replace -

if(k=0)
 printf("This is the end...");

with

if(k=1)
  printf("This is the end...");

and see the changes in the result.

Clue: 0=false

CPallini 12-Oct-16 4:01am

5.

Stemm33 12-Oct-16 4:04am

I get it!Thank you very much!

CPallini · Accepted Answer · 2016-10-11T22:00:00

Solution 2

As suggested by Suvendu Shekhar Giri, you are using the assignment operator instead of the test for equality. Now in C programming language, the construct

C

i=40

is an expression, whoose evaluation is 40. So writing

C

if (i=40)

ends up in

C

if (40)

That is a true condition in the if (any number but 0 is assumed to be true)

That's the reason you're getting such unexpected output.

Posted 11-Oct-16 22:00pm

CPallini

Comments

Suvendu Shekhar Giri 12-Oct-16 4:02am

Indeed, an useful explaination. That's what OP is looking for.
My 5!

CPallini 12-Oct-16 4:06am

Thank you.

Stemm33 12-Oct-16 4:05am

Now its more understood!Thank you!

CPallini 12-Oct-16 4:06am

You are welcome.

Patrice T · Accepted Answer · 2016-10-11T22:09:00

Quote:
Why the result is onetwothree40 50 0 and not onetwothreethis is the end...40 50 0 ?

Because in C, any integer is true but the value 0 which is false.
Be careful, while assinging a value in a if condition is legal, it is often unwanted and a common error of newbies.

Here is links to references books on C and C++ by the authors of the languages. Note than C is the ancestor of C++, so knowing C is always useful with C++.
The C Programming Language - Wikipedia, the free encyclopedia[^]
https://hassanolity.files.wordpress.com/2013/11/the_c_programming_language_2.pdf[^]
http://www.ime.usp.br/~pf/Kernighan-Ritchie/C-Programming-Ebook.pdf[^]

C++ Programing Language[^]

Why the result is onetwothree40 50 0 and not onetwothreethis is the end...40 50 0 ?

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