C++ Functions

Question 1

toupper() & tolower()

Answer 1

Function

toupper converts a character to uppercase. tolower converts a character to lowercase.

• Included in the standard library.
• Only works with char.

Syntax

char ch = 'a';

char upper = toupper(ch); // Converts 'a' to 'A'
char lower = tolower(ch); // Converts 'a' to 'a' (no change)

Question 2

stoi()

Answer 2

Function

stoi is a C++ function used to convert a string to an integer.

• It’s included in the <string> library.</string>
• stoi doesn’t work with strings containing non-integer characters or numbers exceeding the integer range.

Syntax

int myInt = stoi(myString);

Question 3

min () and max()

Answer 3

Function

In C++, the min function returns the smaller of two values, while the max function returns the larger of two values.

• Included in the <algorithm> header.
• Also works with char and string.

Syntax

float a = 3.5;
float b = 2.0;
float result = std::min(a, b); // result will be 2.0

Question 4

setprecision()

Answer 4

Function

setprecision() is a C++ function that sets the decimal precision for output, controlling the number of decimal places in floating-point values.

• included in the iomanip header
• does not work with integer values
• the fixed and scientific prefixes respectively work with decimal places and significant figures

Syntax

int main() {
    double num = 123.456789;

    cout << fixed << setprecision(2) << num << endl; // Displays as fixed-point with 2 decimal places.
    cout << scientific << setprecision(2) << num << endl; // Displays in scientific notation with 2 decimal places.
		

Question 5

.length () and .size()

Answer 5

Function

In C++, .length() is used for strings to get the number of characters, while .size() is a general method for containers to retrieve their size (element count).

• Both can be used to find the length of a string variable.
• .size can also be used to fine the element size in an array.
• Only .length is included in the <string> header

Syntax

string str = "Hello, World!";
    
    // Using .size() to get the length of the string
    cout << "Length using .size(): " << str.size() << endl;
    
    // Using .length() to get the length of the string
    cout << "Length using .length(): " << str.length() << endl;
    

Question 6

pow()

Answer 6

Function

pow() is a C++ function used to calculate the power of a number. It raises a given base to a specified exponent.

• Included in the <cmath> library.
• Does not work with complex numbers.

Syntax

double result = pow(base, exponent);

Question 7

round(), floor(), and ceil()

Answer 7

Function

The round function is used to round a floating-point number to the nearest integer

The floor function rounds a floating-point number down to the nearest integer.

The ceil function rounds a floating-point number up to the nearest integer.

• All are part of the <cmath> library
• They do not work with non-numeric values

Syntax

    double num = 5.7;
    cout << "Round: " << round(num) << endl;
    cout << "Floor: " << floor(num) << endl;
    cout << "Ceiling: " << ceil(num) << endl;
		

Question 8

sqrt()

Answer 8

Function

sqrt() is a C++ function used to calculate the square root of a number.

• Included in the <cmath> header.
• Does not work with complex data types.

Syntax

double result = sqrt(16.0)

Question 9

abs() and fabs()

Answer 9

Function

abs() and fabs() are functions in C++ that are used to calculate the absolute value of a number.abs() works with integers only. fabs() works with floating point numbers.

• Included in the<cmath> library.
• They do not work with non-numeric data types.

Syntax

    int integerNum = -5;
    double floatingNum = -5.67;

    int absoluteInt = abs(integerNum);
    double absoluteFloat = fabs(floatingNum);
		

Question 10

rand()

Answer 10

Function

rand() is a C++ function for generating pseudo-random integers.

• Included in <cstdlib> library.
• Doesn’t work with non-integer data types.

Syntax

int randomNum = rand();