Increment/Decrement Operator

general
1

Programming in C:
I have run the following code:
…
int I = 5;
printf("%d,%d,%d",I++,I,++I);
…

The output I expected was 667.After running this code it was 677.
Could anyone explain this?

2

You can see some explanation here itself…

3

thanks sir

4

Before asking these type of Q, atleast google first. Its one of the most basic question of this operator.

1 Like
5

yes it is sir. But, look carefully please. I have already used associativity and stack concept of storing by printf and later printing in lifo order. Couldn’t find any explanation for this error. plz help:)

6

Good.You ought to tell what you did, and how is it being a problem. If you dont tell about your attempt, then it will be seen as you didnt even bother to search/google it.

7

In C, C++, you should always tend to avoid multiple increments in a single line. The reason is told by your IDE-

C:\project\sasa\main.cpp|29|warning: operation on 'l' may be undefined [-Wsequence-point]|
C:\project\sasa\main.cpp|29|warning: operation on 'l' may be undefined [-Wsequence-point]|
C:\project\sasa\main.cpp|29|warning: operation on 'l' may be undefined [-Wsequence-point]|
C:\project\sasa\main.cpp|29|warning: operation on 'l' may be undefined [-Wsequence-point]|

If you try printing printf("%d %d %d %d %d",l++,l,++l,l++,++l); then it prints 8 9 9 6 9 for l=5 . How will you explain the second last 6?

Multiple increments using “++” in a single line must be avoided. I still remember my professor saying that this gives undefined behavior, you cannot predict what it can print until you see whats printed.

8

noted sir.

9

ohkay sir. thanks for suggestion.