**Course Title:** Mastering C: From Fundamentals to Advanced Programming **Section Title:** Control Structures and Functions **Topic:** Conditional statements: if, else, switch. **Introduction** In the previous topics, we covered the basics of C programming, including variables, data types, and operators. Now, it's time to explore control structures, which allow us to control the flow of our program's execution. Conditional statements are a crucial part of control structures, enabling us to make decisions based on conditions or values. In this topic, we'll delve into the three primary conditional statements in C: `if`, `else`, and `switch`. **1. If Statement** The `if` statement is the simplest conditional statement in C. It allows us to execute a block of code if a certain condition is true. The general syntax is: ```c if (condition) { // code to execute if condition is true } ``` Here, `condition` is a boolean expression that evaluates to either `1` (true) or `0` (false). If the condition is true, the code inside the curly brackets is executed. **Example:** ```c #include <stdio.h> int main() { int x = 10; if (x > 5) { printf("x is greater than 5\n"); } return 0; } ``` In this example, since `x` is indeed greater than 5, the message "x is greater than 5" will be printed. **2. If-Else Statement** The `if-else` statement allows us to execute a different block of code if the condition is false. The general syntax is: ```c if (condition) { // code to execute if condition is true } else { // code to execute if condition is false } ``` **Example:** ```c #include <stdio.h> int main() { int x = 10; if (x > 20) { printf("x is greater than 20\n"); } else { printf("x is less than or equal to 20\n"); } return 0; } ``` In this example, since `x` is not greater than 20, the message "x is less than or equal to 20" will be printed. **3. If-Else Ladder** The `if-else` ladder is a series of `if-else` statements that allow us to check multiple conditions and execute different blocks of code based on the conditions. The general syntax is: ```c if (condition1) { // code to execute if condition1 is true } else if (condition2) { // code to execute if condition1 is false and condition2 is true } else { // code to execute if all conditions are false } ``` **Example:** ```c #include <stdio.h> int main() { int x = 10; if (x > 20) { printf("x is greater than 20\n"); } else if (x == 10) { printf("x is equal to 10\n"); } else { printf("x is less than 10\n"); } return 0; } ``` In this example, since `x` is equal to 10, the message "x is equal to 10" will be printed. **4. Switch Statement** The `switch` statement allows us to execute different blocks of code based on the value of a variable. The general syntax is: ```c switch (expression) { case value1: // code to execute if expression equals value1 break; case value2: // code to execute if expression equals value2 break; default: // code to execute if expression does not equal any value break; } ``` **Example:** ```c #include <stdio.h> int main() { int x = 2; switch (x) { case 1: printf("x is equal to 1\n"); break; case 2: printf("x is equal to 2\n"); break; default: printf("x is not equal to 1 or 2\n"); break; } return 0; } ``` In this example, since `x` is equal to 2, the message "x is equal to 2" will be printed. **Key Concepts and Takeaways** * Conditional statements allow us to control the flow of our program's execution. * The `if` statement executes a block of code if a condition is true. * The `if-else` statement executes a different block of code if the condition is false. * The `if-else` ladder allows us to check multiple conditions and execute different blocks of code. * The `switch` statement executes different blocks of code based on the value of a variable. * Always use curly brackets `{}` to enclose blocks of code. * Use `break` statements to exit the `switch` statement. **Further Reading** For more information on conditional statements, you can refer to the following resources: * The C Programming Language, 2nd Edition by Brian Kernighan and Dennis Ritchie (https://www.cprogramming.com/book/) * C Standard Library, Section 6.8.4.1 The if statement (http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf) **Leave a comment or ask for help** If you have any questions or need help with any of the concepts covered in this topic, please leave a comment below.