🟢 Foundation · Lesson 09

Operators in C++

Q: What is the difference between = and == in C++?

A single = is the assignment operator, which stores a value in a variable. A double == is the equality operator, which compares two values and gives true or false. Mixing them up, especially inside if conditions, is a very common bug.

Q: What is the difference between ++i and i++ in C++?

Both increase i by one, but they differ in what they evaluate to. Pre-increment ++i increases first and then gives the new value, while post-increment i++ gives the old value first and then increases. The difference only matters when the result is used in a larger expression.

Q: What is the ternary operator in C++?

The ternary operator ?: is a compact if-else that returns a value. In condition ? a : b, if the condition is true the result is a, otherwise it is b. It is handy for short choices like max = (x > y) ? x : y;.

What are operators?

Operators are symbols that tell C++ to do something with values — add them, compare them, combine conditions, and so on. Learning the main groups covers almost everything you need for day-to-day code.

Arithmetic operators

Operator	Meaning	Example (a=7, b=2)
`+`	Add	`a + b` → 9
`-`	Subtract	`a - b` → 5
`*`	Multiply	`a * b` → 14
`/`	Divide	`a / b` → 3
`%`	Remainder	`a % b` → 1

💡 Integer division

7 / 2 gives 3, not 3.5, because both are integers. Make one a double — 7.0 / 2 — to keep the decimals.

Relational operators

These compare two values and give a bool (true or false): == equal, != not equal, <, >, <=, >=.

C++

cout << (5 > 3) << " " << (5 == 3);   // prints 1 0

Logical operators

These combine conditions: && (AND, both true), || (OR, at least one true), ! (NOT, flips it).

C++

int age = 20;
bool ok = (age >= 18) && (age < 60);   // true

Assignment & compound

= assigns; compound forms combine an operation with assignment: +=, -=, *=, /=, %=.

C++

int total = 10;
total += 5;    // same as total = total + 5;  → 15
total *= 2;    // → 30

Increment and decrement

++ adds one, -- subtracts one. Placement matters when used inside a bigger expression:

C++

int i = 5;
cout << i++ << "\n";   // prints 5, then i becomes 6
cout << ++i << "\n";   // i becomes 7, then prints 7

Output:
5
7

The ternary operator

A one-line if-else that produces a value:

C++

int x = 8, y = 12;
int max = (x > y) ? x : y;   // 12
cout << "Larger: " << max;

Output:
Larger: 12

Operator precedence

Like maths, some operators bind tighter than others: * and / before + and -, comparisons before && and ||. When in doubt, add parentheses:

C++

int r = 2 + 3 * 4;         // 14, not 20
int r2 = (2 + 3) * 4;      // 20

Common mistakes

Using = (assign) where you meant == (compare) in an if.
Expecting / on two ints to keep decimals — it does not.
Confusing i++ and ++i inside a larger expression.
Forgetting precedence and getting a surprising result — use parentheses.

🏋️ Practice

Read two integers and print their sum, difference, product, integer quotient and remainder. Then use the ternary operator to print which one is larger.

Summary

Arithmetic: + - * / %; watch integer division.
Relational and logical operators give true/false.
Compound assignment (+= etc.) shortens common updates.
++/-- pre vs post matters inside expressions.
The ternary ?: is a compact if-else; parentheses control precedence.

Frequently Asked Questions

What are operators in C++?

Operators are symbols that perform operations on values and variables, such as + for addition or == for comparison. C++ groups them into arithmetic, relational, logical, assignment, bitwise and a few special operators like increment and the ternary.

What is the difference between = and == in C++?

A single = is the assignment operator, which stores a value in a variable. A double == is the equality operator, which compares two values and gives true or false. Mixing them up, especially inside if conditions, is a very common bug.

What is the difference between ++i and i++ in C++?

Both increase i by one, but they differ in what they evaluate to. Pre-increment ++i increases first and then gives the new value, while post-increment i++ gives the old value first and then increases. The difference only matters when the result is used in a larger expression.

What is the ternary operator in C++?

The ternary operator ?: is a compact if-else that returns a value. In condition ? a : b, if the condition is true the result is a, otherwise it is b. It is handy for short choices like max = (x > y) ? x : y;.

What is operator precedence in C++?

Operator precedence decides the order in which operators are evaluated in an expression, much like maths where multiplication happens before addition. When the order is unclear, you use parentheses to force the grouping you want and make the expression readable.

Operators क्या हैं?

Operators वे प्रतीक हैं जो C++ को values के साथ कुछ करने को कहते हैं — जोड़ना, तुलना, conditions जोड़ना, इत्यादि। मुख्य समूह सीखना रोज़मर्रा के code के लिए लगभग सब कुछ कवर कर देता है।

Arithmetic operators

Operator	अर्थ	उदाहरण (a=7, b=2)
`+`	जोड़	`a + b` → 9
`-`	घटाव	`a - b` → 5
`*`	गुणा	`a * b` → 14
`/`	भाग	`a / b` → 3
`%`	शेषफल	`a % b` → 1

💡 Integer division

7 / 2 3 देता है, 3.5 नहीं, क्योंकि दोनों integers हैं। दशमलव रखने को एक को double बनाएँ — 7.0 / 2।

Relational operators

ये दो values की तुलना करके एक bool (true या false) देते हैं: == बराबर, != बराबर नहीं, <, >, <=, >=।

C++

cout << (5 > 3) << " " << (5 == 3);   // 1 0 print karta hai

Logical operators

ये conditions जोड़ते हैं: && (AND, दोनों true), || (OR, कम-से-कम एक true), ! (NOT, इसे पलटता है)।

C++

int age = 20;
bool ok = (age >= 18) && (age < 60);   // true

Assignment और compound

= assign करता है; compound रूप एक संक्रिया को assignment से जोड़ते हैं: +=, -=, *=, /=, %=।

C++

int total = 10;
total += 5;    // total = total + 5 jaisa;  → 15
total *= 2;    // → 30

Increment और decrement

++ एक जोड़ता है, -- एक घटाता है। किसी बड़े expression में इस्तेमाल होने पर स्थान मायने रखता है:

C++

int i = 5;
cout << i++ << "\n";   // 5 print, phir i 6 ho jata hai
cout << ++i << "\n";   // i 7 ho jata hai, phir 7 print

Output:
5
7

Ternary operator

एक-line का if-else जो value देता है:

C++

int x = 8, y = 12;
int max = (x > y) ? x : y;   // 12
cout << "Larger: " << max;

Output:
Larger: 12

Operator precedence

गणित की तरह, कुछ operators दूसरों से ज़्यादा कसकर बँधते हैं: + और - से पहले * और /, && तथा || से पहले तुलनाएँ। संदेह हो तो कोष्ठक जोड़ें:

C++

int r = 2 + 3 * 4;         // 14, 20 nahi
int r2 = (2 + 3) * 4;      // 20

आम गलतियाँ

if में == (तुलना) की जगह = (assign) इस्तेमाल करना।
दो ints पर / से दशमलव रखने की उम्मीद करना — यह नहीं रखता।
बड़े expression के अंदर i++ और ++i को भ्रमित करना।
Precedence भूलकर चौंकाने वाला परिणाम पाना — कोष्ठक इस्तेमाल करें।

🏋️ अभ्यास

दो integers पढ़ें और उनका योग, अंतर, गुणनफल, integer भागफल और शेषफल print करें। फिर ternary operator से print करें कि कौन-सा बड़ा है।

सारांश

Arithmetic: + - * / %; integer division का ध्यान रखें।
Relational और logical operators true/false देते हैं।
Compound assignment (+= आदि) आम updates छोटा करता है।
++/-- pre बनाम post expressions के अंदर मायने रखता है।
Ternary ?: संक्षिप्त if-else है; कोष्ठक precedence नियंत्रित करते हैं।

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