C Programming - Control Instructions - Discussion

do while is used to print statements at least once.

Is, for loop is used to print statements at least once.

Option 4 is correct.

Watch carefully that its written "can be used" in the question.

You can also do this.

for(;(statement);)
{
(---------)
}

For eg.

int main()
{
int i=5;
for(;i--;)
{
printf("%d ",i);
}
}

Or you can also do this

int main()
{
int i=2;
for(i--;i;)
printf("%d",i);
}

If you want the statements inside the loop must execute at least once then you need do-while loop. I disagree somehow on the truth of Statement 4.

I am not agree with 4th statement. Who is agree with 4th statement, please explain how to do following program using for loop & having same answer as after this program execution.

void main()
{
int i=10;
do
{
i++;
printf("i=%d",i);
}while(i<10);
}

This program is gives you answer 11;

Note: If you think about for(;;) statement than we get same answer with while(1) statement also. i.e. I want to say is for & wile are entry controlled block & do....while is exit controlled block.....any one having different suggestion please reply to this post.

Statement 4 is true in case of do while loop not in case of for loop. Let assume if condition is false initially then for loop never executed. So 4th statement is wrong for for loop.

Check the program below:

#include<stdio.h>
int main()
{
int i=0;
for(printf("hi");i>5;i++);
return 0;
}

Statement printf("hi"); which is inside for loop is getting executed even condition is wrong. This cannot be done in while.

So I think 4th option is also correct.

How the 4th statement is true? oly in do while the statement will get execute at least once. In for loop if the condition fails during 1st iteration itself then the statement will not get executed isn't it?

Can anyone tell me how while is faster than for loop?

Why Statement 4 is true.

For Cannot be executed "at-least once", We can terminate it in the first Conditional comparison.

Example:

for(i=1; i>5 ; i++) {"This will not be executed"}.

And If You are genius enough to make it exec atleast once than I may say that -

It is also Possible for "do-while" NOT to execute even atleast for once.

Example:

do{
break; //below lines will not be executed even for a single run.
}
(I know this is stupidity, but what about other programs given by others? )