Relational operators in ‘C’

Relational operators in ‘C’

• Relational operators do some kind of evaluation on the operands and then return value 1(for true) or 0(for false). 
• Relational operators are binary operators because they require two operands to operate. 
• The relational operators are evaluated left to right.

The available Relational operators in the ‘C’ programming language are shown in Figure 1. So use it for the evaluation.

Equal to (==):

First relational operator is ‘==’ (Equal to).

Syntax: expression1 == expression2

Please note the ‘==’(double equal to) sign here. Most of the beginners make mistakes by mentioning the single ‘=’ sign. So, the single ‘=’ sign is the assignment operator, not = (equal to) operator. You have to use double equal to(==) sign for equal to operator.

For example, you have two variables, a and b. And if you want to check whether a is equal to b, then you have to use the double equal to(==) operate. So, a == b returns 1 if a and b are the same. That’s very simple to understand.  

Greater than (>):

Syntax: expression1 > expression2

>(greater than) is another relational operator for greater than evaluation.

a>b, this expression returns 1 if a is larger than b.

Less than (<):

< is for Less than.

Syntax: expression1 < expression2

The less than operator checks if expression1 is less than expression2. If expression1 is less, it returns true(1); otherwise, it returns false(0).

Greater than or equal to (>=):

Syntax: expression1 >= expression2

The greater than or equal to operator checks if expression1 is greater than or equal to expression2. If expression1 is greater or equal, it returns true; otherwise, it returns false.

a>=b returns 1, if a is larger than or equal to b

Less than or equal to (<=):

Syntax: expression1 <= expression2

The less than or equal to operator checks if expression1 is less than or equal to expression2. If expression1 is less or equal, it returns true; otherwise, it returns false.

Not equal to (!=):

Syntax: expression1 != expression2

Suppose if you do a!= b, this expression returns 1 if a is not equal to b. So, if a == b, then this expression will give you 0. That’s why relational operators are evaluation operators. So, they will either turn into 1 or 0. 

‘True’ and ‘False’ in C

• In ‘C,’ Zero is interpreted as false and anything non-zero is interpreted as true. 

In ‘C,’ 0 is false, and anything non-zero is true. So, -1 is true, -9 is true, so non-zero means true in ‘C’. 

• The expressions using relational operators evaluate to a value of either TRUE(1) or FALSE(0). 
• Relational expressions are often used within if and while statements. 

Examples:

Let’s see some examples.

You have two variables, A and B. A=10 and B=20. 

Let’s take a look at the C= (A==B) statement. This is a valid ‘C’ statement. Remember that ‘=‘ is the assignment operator, and ‘==‘ is equal to operator. Here, look into this expression A == B, which means you are checking whether A is really equal to B or not. If A and B are the same value, then this expression evaluates to be TRUE(1); otherwise, FALSE(0). Since A is not equal to B in reality, the A==B expression is evaluated to be FALSE(0). So, C = 0 in this case. 0 will be stored in C. 

Here, take C=(A<=B) this expression. This expression will yield you 1 because A is less than B. So, C = 1 in this case. 

Let’s look into this C=(A!= B) expression,  which is true. A is not equal to B. So, C will be 1 in this case.

Take C= (A<B).In this expression, A is less than B. So, C=1.

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