Control Statements in C

1. Conditional Statements!

In generally,  a C program runs line by line. But sometimes you want your program to make decisions. That’s where conditional statements (also called decision-making statements) come in.

Example, suppose you are going outside, there is two conditions: 

  • If it’s raining  → take an umbrella.

  • If it’s sunny  → wear sunglasses.

So, you are deciding based on a condition. In the same way, C uses conditional statements to decide what to do.

⭐ Now start with types of Conditional Statements.

1️⃣ if statement

Used when you want to do something only if the condition is true.

// Structure
if (condition) {
// code runs only if condition is true
}

🍭Example

// code<>
int age = 20;
if (age >= 18) {
printf("You can vote.\n");
}

Output

You can vote.

2️⃣ if-else statement

Used when you want two possible outcomes (true or false).

//  Structure
if (condition) {
// code if true
} else {
// code if false
}

🍭Example

// code<>
int age = 16;
if (age >= 18) {
printf("You can vote.\n");
} else {
printf("You cannot vote.\n");
}

Output:

You cannot vote.

3️⃣ nested if statement

An if inside another if. Used when you want to check multiple conditions.

🍭Example:

// code<>
int marks = 85;
if (marks >= 60) {
if (marks >= 90) {
printf("Grade: A+\n");
} else {
printf("Grade: A\n");
}
}

Output:

Grade: A

4️⃣ if-else-if ladder

Used when you have many conditions.

🍭Example:

// code<>
int marks = 72;
if (marks >= 90) {
printf("Grade: A\n");
} else if (marks >= 75) {
printf("Grade: B\n");
} else if (marks >= 50) {
printf("Grade: C\n");
} else {
printf("Fail\n");
}

Output:

Grade: C

5️⃣ switch statement

A cleaner way to handle multiple choices instead of many if-else.

🍭Example:

// code<>
int day = 3;
switch(day) {
case 1: printf("Monday\n"); break;
case 2: printf("Tuesday\n"); break;
case 3: printf("Wednesday\n"); break;
default: printf("Invalid Day\n");
}

Output:

Wednesday

At a glance: –

  • Conditional statements = decision makers of C.

  • Types:

    • if (one condition)

    • if-else(two outcomes)

    • nested if (condition inside condition)

    • if-else-if ladder (multiple conditions)

    • switch (multiple fixed choices)

 
An important analogy: –

Just like you decide daily whether to take an umbrella, wear sunglasses, or stay home, a C program uses conditional statements to make decisions.

2. Looping Statements!

Looping Statements in C (Iteration): 

By default, a program runs line by line and then ends. But what if you want to repeat a task multiple times? That’s where loops (looping statements) come in.

🍭Example:

Think about brushing your teeth:

  • You move the brush left → right → left → right repeatedly.

  • Instead of doing it manually one by one, you repeat the same action in a loop.

In the same way, loops in C allow you to run code again and again until a condition is false.

 

Types of Looping Statements in C: –

1️⃣ while loop

Repeats code as long as condition is true.

// Structure
while (condition) {
// code to execute
}

🍭Example:

// code<>
int i = 1;
while (i <= 5) {
printf("%d\n", i);
i++;
}

Output: 

1 
2 
3 
4 
5

2️⃣ do…while loop

Similar to while, but runs at least once, even if condition is false.

// Structure
do {
// code
} while (condition);

🍭Example:

// code<>
int i = 1;
do {
printf("%d\n", i);
i++;
} while (i <= 5);

Output: 

1 
2 
3 
4 
5

3️⃣ for loop

Best when you know exactly how many times to repeat.

// Structure
for (initialization; condition; update) {
// code
}

🍭Example:

// code<>
for (int i = 1; i <= 5; i++) {
printf("%d\n", i);
}

Output:

1 
2 
3 
4 
5

⭐Teacher says “Write this sentence 5 times” → you know the count.

4️⃣ Nested Loops

A loop inside another loop.

🍭Example: Printing a star pattern ‘⭐’

// code
for (int i = 1; i <= 3; i++) {
for (int j = 1; j <= i; j++) {
printf("* ");
}
printf("\n");
}
Output:
 
* 
* * 
* * *
At a glance:

  • while (Repeat until condition fails (unknown count)).

  • do…while (Run at least once, then check).

  • for (Best for fixed repetitions).

  • nested loops (Loop inside a loop (used for patterns, tables, etc.)).

 

An important analogy:

  • while (Keep eating until you are full).

  • do…while (Taste food at least once).

  • for (Counted repetition (do exercise 10 times)).

3. Jumping statements!

In C, jump statements are used to change the normal flow of a program. Instead of going line by line, they allow you to:

  • Exit from a loop early

  • Skip some part of code

  • Jump to another location in the program

🍭Example:

Imagine you are watching a movie :

  • If it’s boring → you exit the theatre early (break).

  • If a scene looks unimportant → you skip to the next scene (continue).

  • If you want to jump directly to a specific scene → you jump to that part (goto).

Types of Jump Statements in C: –

1️⃣ break statement

Used to exit a loop or switch immediately.

// Structure
for (int i = 1; i <= 10; i++) {
if (i == 5) {
break; // loop stops here
}
printf("%d\n", i);
}

Output:

1 
2 
3 
4

🍭 Leaving the cinema hall, when the movie becomes boring.

2️⃣ continue statement

Skips the current iteration and moves to the next iteration.

// Structure
for (int i = 1; i <= 5; i++) {
if (i == 3) {
continue; // skip 3
}
printf("%d\n", i);
}
 
Output: 
 
1 
2 
4 
5
🍭 Skipping a song in a playlist but still continuing with the next songs.
 
 
3️⃣ goto statement:
Jumps directly to a label in the program.
Not recommended in modern coding (makes code messy), but still part of C.
// Structure
int i = 1;
start: 
printf("%d\n", i);
i++;
if (i <= 5) {
goto start; // jump back to label
}

Output:

1 
2 
3 
4 
5

Using a shortcut road to reach a place instead of following the regular route.

At a glance: 

  • break → exits loop/switch immediately.

  • continue → skips the current step and moves to the next.

  • goto → jumps to a label (used rarely).

Analogy:

  • break = quitting the game early.

  • continue = skipping a level, but keep playing.

  • goto = teleporting to another level.

4. Flowcharts & Dry runs!

When learning C, just writing code is not enough. To understand how a program works, programmers use two powerful tools:

  1. Flowcharts → Pictorial representation of logic.

  2. Dry Run → Step-by-step manual execution of the code.

1. Flowcharts in C: 

A flowchart is a diagram that shows the flow of a program using different shapes like rectangles, diamonds, and arrows.

🔗Symbols in Flowchart:

  • Oval (Ellipse) → Start / End

  • Rectangle → Process (like calculation)

  • Diamond → Decision (like if/else)

  • Parallelogram → Input/Output

🍭Example: Think about making tea. 

  1. Start

  2. Boil water

  3. Add tea leaves

  4. If milk available?

    • Yes → add milk

    • No → continue without milk

  5. Serve

  6. End

This can be shown in a flowchart 👇

(START) → [Boil Water] → [Add Tea Leaves] → ◇(Milk available?) 
YES → [Add Milk] 
NO → [Skip] 
→ [Serve Tea] → (END)

Same way, before coding in C, programmers often draw a flowchart to plan logic.

2. Dry Run in C:

A dry run means manually executing the program line by line on paper, without actually running it on the computer.

It helps in debugging and checking logic.

🍭Example: Imagine your teacher gives you math homework :
Before solving in your notebook, you think step by step in your mind → this is a dry run.

Dry Run: –

// code<>
#include <stdio.h>
int main() {
int i, sum = 0;
for (i = 1; i <= 5; i++) {
sum = sum + i;
}
printf("%d", sum);
return 0;
}

Dry Run Table:

Stepisum (before)sum (after)
1101 (0+1)
2213 (1+2)
3336 (3+3)
44610 (6+4)
551015 (10+5)

 

At a glance: – 

  • Flowchart = Diagram to plan program logic.

  • Dry Run = Manually checking how variables change step by step.

Analogy: 

  • Flowchart = Google Maps route before travel.

  • Dry Run = Walking through the path mentally before going.

✋
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