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C++ Basic Data Types

I. In-Class Exercises

Programming Exercises

Output Practice: L1051
Type Conversion Practice: L1052

Sample Code

1
2#include "CTurtle.hpp"
3#include <bits/stdc++.h>
4using namespace std;
5using namespace cturtle;
6
7int main() {
8    // Create a canvas screen
9    TurtleScreen scr;
10    // Create a drawing turtle
11    Turtle turtle(scr);
12
13        turtle.right(50);
14        turtle.forward(22.5);
15        turtle.right(50);
16        turtle.forward(22.5);
17        turtle.right(50);
18        turtle.forward(22.5);
19        turtle.right(50);
20        turtle.forward(22.5);
21        turtle.right(50);
22        turtle.forward(22.5);
23        turtle.right(50);
24        turtle.forward(22.5);
25        turtle.right(50);
26        turtle.forward(22.5);
27        turtle.right(50);
28        turtle.forward(22.5);
29        turtle.right(50);
30        turtle.forward(22.5);
31        turtle.right(50);
32        turtle.forward(22.5);
33        turtle.right(50);
34        turtle.forward(22.5);
35        turtle.right(50);
36        turtle.forward(22.5);
37        turtle.right(50);
38        turtle.forward(22.5);
39        turtle.right(50);
40        turtle.forward(22.5);
41        turtle.right(50);
42        turtle.forward(22.5);
43        turtle.right(50);
44        turtle.forward(22.5);
45
46        // Pause the program
47        system("pause");
48        // End of program
49        return 0;
50}

1//
2#include "CTurtle.hpp"
3#include <bits/stdc++.h>
4using namespace std;
5using namespace cturtle;
6
7int main() {
8        cout << 10 << endl;
9        cout << "10: " << sizeof(10) << endl;
10        cout << sizeof(2147483647) << endl;
11        cout << sizeof(2147483648) << endl;
12        cout << sizeof(int) << endl;
13        cout << sizeof(long long) << endl;
14        cout << 10.4 << endl;
15        cout << sizeof(10.4) << endl;
16        cout << sizeof(float) << endl;
17        cout << sizeof(double) << endl;
18        cout << 10.0 << endl;
19        cout << "10.0: " << sizeof(10.0) << endl;
20        cout << "Hello, world!" << endl;
21        cout << "e" << endl;
22        cout << sizeof("e") << endl;
23        cout << 'e' << endl;
24        cout << sizeof('e') << endl;
25        cout << 1 << endl;
26        cout << 1.0 << endl;
27        cout << '1' << endl;
28        cout << true << endl;
29        cout << false << endl;
30        cout << (bool)3.5 << endl;
31        cout << float(3.5) << endl;
32        cout << static_cast<int>(3.5) << endl;
33        cout << 'a' + 1 << endl;
34        cout << true + 'a' << endl;
35        return 0;
36}

1//
2#include <bits/stdc++.h>
3using namespace std;
4
5int main() {
6        cout << "10 + 3 = " << 10 + 3 << endl;
7        cout << "10 * 3 = " << 10 * 3 << endl;
8        cout << "10 / 3 = " << 10 / 3 << endl;
9        return 0;
10}

1//
2#include <bits/stdc++.h>
3using namespace std;
4
5int main() {
6        cout << (char)48 << endl;
7        cout << bool(10) << endl;
8        cout << (int)'A' << endl;
9        cout << (int)10.9 << endl;
10        cout << char('z' - 1) << endl;
11        return 0;
12}

II. Knowledge Summary

✨ Four Basic Data Types

Integer Types (int/long long, etc.)

Integer types are used to store numbers without decimal parts and are the most commonly used data types in competitive programming. Different integer types occupy different memory sizes and can represent different ranges. Generally, int is sufficient; when data exceeds 2.1 billion (2^31-1), use long long. Adding the unsigned prefix indicates an unsigned integer that can only store non-negative numbers but has double the range.

Keyword	Memory Size	Data Range
short	16 bits / 2 bytes	-2^15 to 2^15 - 1 / -32768 to 32767
int (default)	32 bits / 4 bytes	-2^31 to 2^31 - 1 / -2147483648 to 2147483647
long	32 bits / 4 bytes	-2^31 to 2^31 - 1 / -2147483648 to 2147483647
long long	64 bits / 8 bytes	-2^63 to 2^63 - 1 / -9223372036854775808 to 9223372036854775807
unsigned short	16 bits / 2 bytes	0 to 2^16 - 1 / 0 to 65535
unsigned int	32 bits / 4 bytes	0 to 2^32 - 1 / 0 to 4294967295
unsigned long	32 bits / 4 bytes	0 to 2^32 - 1 / 0 to 4294967295
unsigned long long	64 bits / 8 bytes	0 to 2^64 - 1 / 0 to 18446744073709551615

Floating-Point Types (float/double)

Floating-point types are used to store numbers with decimal parts. Different floating-point types have different precision: float is accurate to 6-7 decimal places, double to 15-16. In competitive programming, double is generally used because it has higher precision and is the default type for decimals in C++ (e.g., 3.14 defaults to double).

Keyword	Memory Size	Data Range
float	32 bits / 4 bytes	±3.4×10^38 / 6-7 decimal places
double (default)	64 bits / 8 bytes	±1.7×10^308 / 15-16 decimal places
long double	128 bits / 16 bytes	±3.4×10^3932 / 33-34 decimal places

Character Type (char)

The character type is used to store a single character, such as letters, digit symbols, or special symbols. Characters are actually stored as integers in the computer, where each character corresponds to an ASCII code value. Therefore, characters can participate in arithmetic operations (e.g., 'a' + 1 gives the ASCII value of 'b').

Keyword	Memory Size	Data Range
char	8 bits / 1 byte	0-127

ASCII Table

Common ASCII values:

ASCII Value	Character	Description
0	`\0`	Null character
32	(space)	Space character
48	`0`	Digit 0
57	`9`	Digit 9
65	`A`	Uppercase A
90	`Z`	Uppercase Z
97	`a`	Lowercase a
122	`z`	Lowercase z
127	DEL	Delete character

ASCII Patterns:

Digits 0-9 correspond to 48-57 (consecutive)
Uppercase letters A-Z correspond to 65-90 (consecutive)
Lowercase letters a-z correspond to 97-122 (consecutive)
The difference between uppercase and corresponding lowercase ASCII values is 32 (e.g., A=65, a=97)

Boolean Type (bool)

The boolean type is used to represent logical true/false, with only two values: true and false. Boolean values are stored as integers in the computer: true corresponds to 1, false to 0. In C++, any non-zero value is treated as true, while 0 is treated as false.

Keyword	Memory Size	Data Range
bool	8 bits / 1 byte	0 (false) to 1 (true)

✨ Type Conversions Between the Four Data Types

Conversion	From Integer	From Float	From Char	From Bool
To Integer	-	Truncates decimal part, e.g., `(int)3.5=3`	Converts via ASCII, e.g., `(int)'0'=48`	`(int)true=1`, `(int)false=0`
To Float	Converts directly, e.g., `(double)3=3`	-	Converts via ASCII, e.g., `(double)'0'=48`	`(double)true=1`, `(double)false=0`
To Char	Converts via ASCII, e.g., `(char)48='0'`	First converts to int then via ASCII, e.g., `(char)48.8='0'`	-	`(char)true='\1'`, `(char)false='\0'`
To Bool	Non-zero becomes true, 0 becomes false, e.g., `(bool)3=1`	Non-zero becomes true, 0 becomes false, e.g., `(bool)3.5=1`	Converts via ASCII, e.g., `(bool)'0'=1`, `(bool)'\0'=0`	-

C++ Basic Data Types

I. In-Class Exercises

Programming Exercises

Sample Code

II. Knowledge Summary

✨ Four Basic Data Types

Integer Types (int/long long, etc.)

Floating-Point Types (float/double)

Character Type (char)

ASCII Table

Boolean Type (bool)

✨ Type Conversions Between the Four Data Types

III. Homework

Programming Exercises

Knowledge Quiz