What Does the Question Mark (?) Character Do in C ?

Exploring the Meaning of the Question Mark Character in C

Introduction

The question mark character ('?') is a multifaceted symbol in C , carrying various meanings and applications. One notable usage of the question mark is within the conditional operator, commonly known as the ternary operator.

Role in the Conditional Operator

Within the conditional operator, the question mark marks the separation between the condition, the true result, and the false result. The syntax is as follows:

condition ? true_result : false_result

If the condition evaluates to true, the expression evaluates to true_result; otherwise, it evaluates to false_result.

Example in Practice

Consider the following code snippet that implements a function to determine whether a queue is empty:

int qempty()
{
    return (f == r ? 1 : 0);
}

In this example, the question mark is employed within the ternary operator. If the condition f == r holds true (indicating an empty queue), the function returns 1. Otherwise, it returns 0.

Alternative Syntax

The conditional operator provides a concise alternative to the traditional if-else statement. The equivalent if-else statement for the above code is:

int qempty()
{ 
  if(f == r)
  {
      return 1;
  } 
  else 
  {
      return 0;
  }
}

Conclusion

The question mark character in C plays a pivotal role within the conditional operator, allowing for efficient and readable code by providing a shorthand representation of if-else statements. Its versatility and time-saving capabilities make it a valuable tool in the C programmer's arsenal.

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