Arithmetic operators - Step-by-Step Execution

Concept Flow - Arithmetic operators

Start

↓

Initialize variables

↓

Apply +, -, *, /, %

↓

Store results

↓

Print results

↓

End

This flow shows how arithmetic operators take variables, perform calculations, store results, and then output them.

Execution Sample

C

int a = 10;
int b = 3;
int sum = a + b;
int diff = a - b;
int prod = a * b;
int div = a / b;
int mod = a % b;
printf("%d %d %d %d %d", sum, diff, prod, div, mod);

This code calculates sum, difference, product, division, and remainder of two integers and prints the results.

Execution Table

Step	Operation	Expression	Result	Explanation
1	Addition	sum = a + b	13	10 + 3 equals 13
2	Subtraction	diff = a - b	7	10 - 3 equals 7
3	Multiplication	prod = a * b	30	10 * 3 equals 30
4	Division	div = a / b	3	Integer division 10 / 3 equals 3 (fraction discarded)
5	Modulo	mod = a % b	1	Remainder of 10 divided by 3 is 1
6	Print	printf(...)	13 7 30 3 1	Outputs all results separated by spaces
7	End	-	-	Program finishes

💡 All arithmetic operations completed and results printed

Variable Tracker

Variable	Initial	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	Final
a	10	10	10	10	10	10	10
b	3	3	3	3	3	3	3
sum	undefined	13	13	13	13	13	13
diff	undefined	undefined	7	7	7	7	7
prod	undefined	undefined	undefined	30	30	30	30
div	undefined	undefined	undefined	undefined	3	3	3
mod	undefined	undefined	undefined	undefined	undefined	1	1

Key Moments - 3 Insights

Why does division of 10 / 3 give 3 instead of 3.333?

In C, dividing two integers results in integer division, which discards the decimal part. See execution_table step 4 where div = 3.

What does the modulo operator (%) do?

Modulo gives the remainder after division. In step 5, 10 % 3 equals 1 because 3 goes into 10 three times with remainder 1.

Are the original variables 'a' and 'b' changed by the operations?

No, 'a' and 'b' keep their initial values throughout. Only new variables store results, as shown in variable_tracker.

Visual Quiz - 3 Questions

Look at the execution_table at step 3, what is the value of 'prod'?

A 7

B 13

C 30

D 3

💡 Hint

Check the 'Result' column for step 3 in execution_table.

At which step does the modulo operation happen?

A Step 2

B Step 5

C Step 4

D Step 1

💡 Hint

Look for the '%' operator in the 'Operation' column in execution_table.

If 'a' was 9 instead of 10, what would be the new value of 'mod'?

A 0

B 1

C 2

D 3

💡 Hint

Modulo is remainder of division; 9 % 3 equals 0, but check carefully.

Concept Snapshot

Arithmetic operators in C:
+ addition
- subtraction
* multiplication
/ integer division (fraction discarded)
% modulo (remainder)
Use with integers to calculate and store results.

Full Transcript

This example shows how arithmetic operators work in C. Variables a and b are set to 10 and 3. Then sum, difference, product, division, and modulo are calculated step-by-step. Division discards decimals because both operands are integers. Modulo gives the remainder after division. The original variables stay unchanged. Finally, all results are printed together.

Practice

1. Which arithmetic operator in C gives the remainder of a division?

easy

A. The multiplication operator (*)

B. The division operator (/)

C. The modulus operator (%)

D. The subtraction operator (-)

Solution

1. Step 1: Understand the modulus operator

   The modulus operator (%) returns the remainder after division of two integers.

2. Step 2: Compare with other operators

   Division (/) returns the quotient, multiplication (*) multiplies, subtraction (-) subtracts.

3. Final Answer:

   The modulus operator (%) -> Option C

4. Quick Check:

   Remainder = % operator [OK]

Hint: Remainder means modulus (%) operator [OK]

Common Mistakes:

• Confusing division (/) with modulus (%)
• Thinking multiplication (*) gives remainder
• Using subtraction (-) for remainder

2. Which of the following is the correct syntax to multiply two integers a and b in C?

easy

A. a x b;

B. a * b;

C. a . b;

D. a & b;

Solution

1. Step 1: Recall multiplication operator in C

   The multiplication operator in C is the asterisk symbol (*).

2. Step 2: Check each option

   a * b; uses '*', which is correct. Options B, C, D use invalid symbols for multiplication.

3. Final Answer:

   a * b; -> Option B

4. Quick Check:

   Multiply with * operator [OK]

Hint: Use * for multiplication in C [OK]

Common Mistakes:

• Using 'x' instead of '*' for multiplication
• Using '.' or '&' mistakenly
• Missing semicolon at end

3. What is the output of this C code?

int a = 7, b = 3;
printf("%d", a / b);

medium

A. 1

B. 2.333333

C. 3

D. 2

Solution

1. Step 1: Understand integer division in C

   Both a and b are integers, so a / b performs integer division, which discards the decimal part.

2. Step 2: Calculate 7 / 3 using integer division

   7 divided by 3 is 2.333..., but integer division returns 2.

3. Final Answer:

   2 -> Option D

4. Quick Check:

   Integer division truncates decimals [OK]

Hint: Integer division drops decimals, result is integer [OK]

Common Mistakes:

• Expecting floating-point result
• Confusing remainder with division result
• Using wrong format specifier in printf

4. Find the error in this C code snippet:

int x = 10;
int y = 3;
int z = x / y.0;
printf("%d", z);

medium

A. Using a floating-point number in integer division

B. Incorrect format specifier in printf

C. Missing semicolon after variable declaration

D. Division by zero error

Solution

1. Step 1: Analyze the division expression

   The expression x / y.0 uses y.0 which attempts a floating-point literal but causes invalid syntax, as x and y are integers.

2. Step 2: Understand the syntax error

   Using y.0 causes a compilation error due to invalid syntax in the integer division context.

3. Final Answer:

   Using a floating-point number in integer division -> Option A

4. Quick Check:

   Integer division must use integers only [OK]

Hint: Integer division needs integer operands only [OK]

Common Mistakes:

• Thinking printf format is wrong
• Ignoring the decimal in y.0
• Assuming division by zero

5. You want to calculate the average of two integers a and b in C and get a floating-point result. Which code snippet correctly does this?

hard

A. float avg = (a + b) / 2.0;

B. float avg = (a + b) / 2;

C. int avg = (a + b) / 2.0;

D. float avg = a / b + 2;

Solution

1. Step 1: Understand integer vs floating-point division

   Dividing by 2 (integer) causes integer division, losing decimals. Dividing by 2.0 (double) forces floating-point division.

2. Step 2: Check each option for correct average calculation

   float avg = (a + b) / 2; does integer division then converts to float, losing decimals. float avg = (a + b) / 2.0; divides by 2.0, giving float result. int avg = (a + b) / 2.0; stores float result in int, losing decimals. float avg = a / b + 2; is incorrect formula.

3. Final Answer:

   float avg = (a + b) / 2.0; -> Option A

4. Quick Check:

   Divide by 2.0 for float average [OK]

Hint: Divide by 2.0 to get float average [OK]

Common Mistakes:

• Dividing by integer 2 causing integer division
• Storing float result in int variable
• Wrong formula for average