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Why the output of below program is not as expected?

0 votes
106 views
#include<stdio.h>
main()
{
        int a=10;
        printf("%d\n",a++==a);
}

Output should be 1 but it is coming as 0,
Can anyone please explain?

posted Sep 14, 2017 by anonymous

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Mine is coming as 1 (http://codepad.org/CHaTPyJs )
So it may be compiler dependent behavior, if operation is executed from left to right then answer would come as zero else 1.

1 Answer

0 votes

Assume, compiler executes statement a++==a from left to right, then
a = 10
a++ becomes 11
so, a++(10) == a(now becomes 11)

answer Sep 15, 2017 by anonymous
Thanks for the answer,
But I don't think, this left to right explanation is right,
Because if this explanation is correct then,
If a++==a is giving o/p 0 then a==a++ should give o/p as 1
It's about precedence.++ Is higher precedence than ==. I think you got the ans
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+3 votes

input: 1 2 3 4 5
output: 5 4 1 2 3 or 1 2 3 5 4

Can any one tell?

+1 vote

I am running below script on sles 11 and getting different output.

#!/bin/bash
PID=$(/bin/ps aux | grep sro-rest | grep -v grep | awk '{print $2}')
echo "PID = $PID"
. /etc/rc.status
PID=$(/bin/ps aux | grep sro-rest | grep -v grep | awk '{print $2}')
echo "PID = $PID"

Output:

PID = 2453
PID =

After debugging, I get to know that once we run . /etc/rc.status then output of ps aux is getting short.
See below script for example,

#!/bin/bash
echo "Before ==================================> "
/bin/ps aux | grep java | grep -v grep
. /etc/rc.status
echo "After ==================================> "
/bin/ps aux | grep java | grep -v grep

Output :

Before ==================================>
root      2453  4.9  7.8 8496196 615020 ?      Sl   Jun05  60:31 /usr/java/jre1.8.0_77//bin/java -Djava.net.preferIPv4Stack=true -Djava.library.path=/opt/sro/lib -Dserver.port=50000 -Dspring.profiles.active=gal -jar /opt/sro/ui/lib/sro-rest-SNAPSHOT.jar
After ==================================>
root      2453  4.9  7.8 8496196 615020 ?      Sl   Jun05  60:31 /usr/java/jre1.8.0_77//bin/java -Djava.net.preferIPv4Stack=true -Djava.l

Can anyone explain why different behavior for the same command?

0 votes
#include<stdio.h>
int main()
{
   int n;
   for(n = 7; n!=0; n--)
     printf("n = %d", n--);
   getchar();
   return 0;
}
+3 votes

1.

main()
{
printf("%x",-1<<4);
}

2.

main()
{
int i=10;
i=!i>14;
Printf ("i=%d",i);
}
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