What is an if-else statement in C?
In C programming, an if-else statement is a conditional construct that runs a specific set of statements depending on whether a condition evaluates to true or false. The 'if' section is triggered when the condition is true, while the 'else' section is triggered when the condition is false.
Syntax of the if-else Statement:
It has the following syntax:
if(expression)
{
// statements;
}
else
{
// statements;
}
Simple Example for if-else Statement
Let's consider an illustration showcasing the if-else statement in the C programming language.
Example
#include <stdio.h>
int main() { //main function
int num;
printf("Enter a number: ");
scanf("%d", &num);
if (num > 0) {
printf("The number is positive.\n");
}
else if (num < 0) {
printf("The number is negative.\n");
}
else {
printf("The number is zero.\n");
}
return 0;
}
Output:
Enter a number: 10
The number is positive.
What is a switch statement in C?
A switch statement is a type of conditional statement frequently employed in C programming to evaluate a variable's value against multiple cases. When a case matches the value, the associated statements are executed. Each case is identified by a specific name or number. The user-input value is compared against each case sequentially until a match is found. If the input value does not match any case, the default statement is executed.
Syntax of the switch statement:
It has the following syntax:
switch(expression)
{
case constant 1:
// statements;
break;
case constant 2:
// statements;
break;
case constant n:
// statements;
break;
default:
// statements;
}
Simple Switch Statement Example in C
Let's consider a scenario to demonstrate the basic switch statement in the C programming language.
Example
#include <stdio.h>
int main() { //main function
int months;
printf("Choose a number (1-5): ");
scanf("%d", &months);
switch(months) {
case 1:
printf("January\n");
break;
case 2:
printf("February\n");
break;
case 3:
printf("March\n");
break;
case 4:
printf("April\n");
break;
case 5:
printf("May\n");
break;
default:
printf("Invalid input! Please choose a number between 1 and 5.\n");
}
return 0;
}
Output:
Choose a number (1-5): 4
April
Key differences between if-else and switch statements
There exist multiple distinctions between the if-else and switch statements in the C programming language. Here are a few key variances:
Definition
In C programming, the if-else statement runs a set of statements depending on a specified condition or expression. When the condition evaluates to true, the 'if' block is executed; otherwise, the 'else' block is run. On the other hand, the switch statement encompasses various cases or options from which the user selects the one to execute.
Expression
In C programming, the if-else statement allows for the inclusion of either a solitary expression or numerous expressions to cater to various conditions. Each expression undergoes evaluation according to specific values or conditions, encompassing both equality and logical assessments. In contrast, the switch statement accommodates a sole expression, which can be either a single integer or a string object. The switch statement exclusively verifies equality expressions.
Evaluation
An if-else construct in C programming is capable of assessing various data types including integers, floating-point numbers, characters, pointers, and Booleans. Conversely, a switch statement is designed to handle integer or character data exclusively.
Sequence of Execution
In an 'if-else' statement, either the 'if' block or the 'else' block is executed depending on the condition. Conversely, in a 'switch' statement, each case is executed sequentially until encountering the break keyword or executing the default statement.
Default Execution
If the specified condition is false in the 'if' statement, the statements within the else block will be executed as a default behavior. Conversely, when the expression in the switch statement does not match any of the cases, the default statement will be executed.
Values
Values are reliant on the condition outlined within the 'if' statement. This condition outcome dictates the execution of either the 'if' or 'else' block. Conversely, the value is typically determined by the user or input in the switch statement. Depending on the specified value, the associated case block is executed, disregarding the other cases.
In C programming, the if-else statement assesses a condition to determine its truth value. Conversely, the switch statement checks the variable's value against various cases. When the value aligns with a case, the corresponding block of statements is executed.
Modifications
Altering an 'if-else' statement can be challenging as eliminating the 'else' part can alter the program's logic and flow. In contrast, making changes to a switch statement is simpler compared to an 'if-else' construct. Removing any case from the switch does not disrupt the execution of other cases, making it easier to modify and manage. Thus, it can be concluded that the switch statement is more convenient for modifications and maintenance.
Speed
In C programming, when there are several options, the speed of 'if-else' statements execution is relatively slower. On the other hand, the switch statement in C creates a jump table with case constants during compilation. This jump table directs the program flow based on the expression value. When faced with multiple options, the switch statement's execution speed surpasses that of an equivalent 'if-else' logic.
Difference between if-else and Switch Statement in C in Tabular Form
There exist various key distinctions between the if-else and switch statements in the C programming language. The primary variances are outlined below in tabular format:
| if-else Statement | switch Statement |
|---|---|
| Executes a block of code if a specified condition is true | Evaluates an expression and matches the value to a case label |
| Supports complex conditions using logical operators | Limited to evaluating a single expression against multiple values |
| Suitable for boolean conditions | Ideal for comparing a single value against multiple options |
| Offers flexibility in condition formulation | Provides a more concise syntax for multiple branch conditions |
| Features | If-else | switch |
|---|---|---|
| Definition | Depending on the condition in the 'if' statement, 'if' and 'else' blocks are executed. | The user will decide which statement is to be executed. |
| Expression | It contains either a logical or an equality expression. | It contains a single expression, which can be either a character or an integer variable. |
| Evaluation | It evaluates all types of data, such as integer, floating-point, character, or Boolean. | It evaluates either an integer or a character. |
| Sequence of execution | First, the condition is checked. If the condition is true, the 'if' block is executed; otherwise, the 'else' block is executed. | It executes one case after another till the break keyword is found, or the default statement is executed. |
| Default execution | If the condition is not true, by default, the else block will be executed. | If the value does not match any case, by default, the default statement is executed. |
| Modification | Modifications is not easy in the 'if-else' statement. | Cases in a switch statement are easy to maintain and modify. Therefore, we can say that the removal or editing of any case will not interrupt the execution of other cases. |
| Speed | If there are multiple choices implemented through 'if-else', the speed of the execution will be slow. | If we have multiple choices, the switch statement is the best option as the speed of execution will be much higher than 'if-else'. |
Conclusion
In summary, the if-else and switch statements hold significant roles as decision-making tools within the C programming language. The if-else statement is frequently employed to assess intricate conditions according to specified values or expressions. Conversely, the switch statement is ideal for comparing a variable against several fixed values. Both statements serve to manage the flow of a program. The switch statement offers simplicity, speed, and ease of maintenance. In contrast, the if-else statement allows for greater adaptability in managing intricate and logical conditions. In essence, these decision-making constructs contribute to streamlining and organizing program logic.