Understanding the If Statement in C – For Absolute Beginners

Imagine you're teaching a robot how to make decisions. For example:

• "If it's raining, take an umbrella."
• "If you're hungry, eat a snack."

This is exactly how the if statement works in C programming. It helps your program make decisions based on conditions.

How Does the If Statement Work?

The if statement checks whether a condition is true or false. If true, it runs a block of code. If false, it skips it.

Basic Syntax:

if (condition) {
    // Code to run if the condition is true
}

Real-Life Example: Checking Exam Results

Let's say you wrote an exam, and the passing mark is 40. Your program should congratulate you only if your score is above 40.

Program:

#include <stdio.h>

int main() {
    int your_score = 75;  // Your exam score
    int passing_mark = 40;  // Minimum marks needed to pass

    printf("Checking your result...\n");

    if (your_score >= passing_mark) {
        printf("Congratulations! You passed!\n");
        printf("Your score: %d/100\n", your_score);
    }

    printf("Result check complete.\n");
    return 0;
}

What Happens?

1. The program checks if your_score (75) is greater than or equal to passing_mark (40).
2. Since 75 >= 40 is true, it runs the code inside { } and prints:

   Congratulations! You passed!
   Your score: 75/100

3. Finally, it prints "Result check complete." because this line is outside the if block.

int your_score = 30;  // You failed

Checking your result...
Result check complete.

Common Mistakes to Avoid

if (score = 50) { }  // This sets score to 50, not a comparison!

if (score == 50) { }  // Checks if score is 50

if (score > 40)
    printf("Passed!\n");  // Only this runs conditionally
    printf("Great job!\n");  // This ALWAYS runs (not part of if)

if (score > 40) {
    printf("Passed!\n");  
    printf("Great job!\n");  // Both run only if true
}

if (score > 40); {  
    printf("This always runs!");  
}

When Do We Use If Statements?

• Checking passwords (if password is correct, allow login).
• Gaming logic (if player health <= 0, game over).
• Temperature control (if temp > 30°C, turn on AC).

if (your_score >= 80) {
printf("Wow! You got a distinction!\n");
}

Summary

• ✅ if helps make decisions in code.
• ✅ It runs code only if the condition is true.
• ✅ Avoid common mistakes like = vs == and missing braces.
• ✅ Used in games, apps, and real-world devices.

Now, try writing your own if statement!