CODEWITHSUNDEEP
coperators
merzy
merzy

Reputation: 17

Issue with using multiple relational operators in C

I'm new to programming, but I searched for this topic before asking and still can't figure out what my program is doing wrong.

I have this:

int i;
do
{
    i = get_int("Enter positive integer between 1-10: \n");
}
while(1>i && i<10)

I want to ask the user for a positive integer between one and ten. it doesn't accept anything less than one, which is good, but it will take anything positive. I understand how I can't do 1>i<10 since it reads it from left to right but I can't get it to recognize it has to follow both operators. What is my issue?

Upvotes: 0

Views: 232

Answers (5)

Vlad from Moscow
Vlad from Moscow

Reputation: 310990

I want to ask the user for a positive integer between one and ten.

I think you want an integer in the range with inclusive 1 and 10.

When how will look such a condition of a valid positive integer?

It will look the following way

1 <= i && i <= 10

So the do while loop must continue its iterations while this condition is not true. So in the condition of the loop you should write a negation of the above condition

int i;

do
{
    i= get_int ("Enter positive integer between 1-10: \n");
} while ( !( 1 <= i && i <= 10 ) );

If to remove the parentheses then the condition will look like

int i;

do
{
    i= get_int ("Enter positive integer between 1-10: \n");
} while ( 1 > i || i > 10 ) );

Upvotes: 0

AdamF
AdamF

Reputation: 2930

you have been mistaken (syntax mistake) inside the while expression (2 mistakes their, the logic is not right and a syntnatx error with 1<i) - see fixes inline:

int i = 0;  /*its better if you initialize the i here*/
do
{
    i= get_int ("Enter positive integer between 1-10: \n");
}
while((i > 1) && (i < 10));

Upvotes: 0

alex01011
alex01011

Reputation: 1702

Your loop condition is incorrect. You should have used logical OR instead of logical AND.

This worked for me.

  do
  {
    i= get_int ("Enter positive integer between 1-10: \n");

  } while (i<1 || i>10);

Upvotes: 0

chux
chux

Reputation: 153498

i can't get it to recognize it has to follow both operators.
Why would it be more applicable when the integer has to meet both criteria?

do {
  ....
} while(test);

When the test returns true, the input is re-tried as the loop iterates again. What is the criteria for re-trying, not what is the criteria for passing.

Input only needs to fail one of two tests to re-try: too low or too high. Hence the need for "or" (||).

} while(i < 1 || i > 10);

Upvotes: 1

Abhishek Bhagate
Abhishek Bhagate

Reputation: 5766

You probably want the loop to run the loop as long as user inputs a number between 1 to 10. Your condition in the while loop isn't correct. It should be as follows -

while(i>1 && i<10); # runs as long as i is in range 1 to 10

However, If you want to break the loop as soon as the user inputs any number inside the 1 to 10 range, then you should use the following -

while(!(i>1 && i<10)); # runs as long as i is outside the range 1 to 10

Upvotes: 1

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