C index

Datatypes

Types

char: Integer is 1 byte.
int: Integer numbers 4 bytes (short is 2 bytes and long is 4 bytes)
float: Single precision floating point is 4 bytes.
double: Double precision floating point is 8 bytes.
void: Absence of type.

Data types

Integer

Allowed types are char and int;

signed char: 8 bit, from -128 to 127.
unsigned char: 8 bit, from 0 to 255.
char: 8 bit, used to store ASCII, ex; 'h', '\n', etc...
short int: 16 bit, from -32,768 to 32,767.
unsigned short int: 16 bit, from 0 to 65,535.
int: 32 bit, from -2,147,483,648 to 2,147,483,647.
unsigned int: 32 bit, from 0 to 4,294,967,295.
long int: 32 bit, from -2,147,483,648 to 2,147,483,647.
unsigned long int: 32 bit, from 0 to 4,294,967,295.
long long int: 64 bit, from 9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
unsigned long long int: 64 bit, from 0 to 18,446,744,073,709,551,615.

Real number

Real numbers are fractional numbers, all floating points are signed. Check float.h.

float: From 1e-37 to 1e37
double: Largest of floating point.
long double: The long double data maybe larger than double

Complex number

Complex Number Types

Enumeration

        enum colors {black, orange, blue} color;
        enum colors color;

Unions

        union accounts {
            int id;
            float value;
        } first_account, second_account;

Structures

        struct point {
            int x, y, z;
        } first_point;
        struct point second_point;

Arrays

        int account_array[9];
        int account_array[] = {0, 1, 2, 3};
        int account_array[] = {0, 1, 2, [9] = 9};

        int account_array[2][9] { {1,2,3},{9,8,7} }

Initializing string with individual characters the null character must be defined;

        char black[] = {'b', 'l', 'a', 'c', 'k', '\0'}

        char black[] = "black";

        union accounts {
            int id;
            float value;
        };
        union accounts accounts_array[9];
        accounts_array[0].id = 8;

        struct point {
            int x, y;
        };
        struct point point_array[9];
        point_array[0].x=2;
        point_array[0].y=3;

Pointers

Incomplete types

Type qualifiers

Storage class

Format Type Specifiers

%c: Character
%s: String of characters
%d: Decimal integer
%f: Decimal floating point
%llu: unsigned long long
%o: Signed octal
%u: Unsigned decimal integer
%x: Unsigned hexadecimal integer
%p: Pointer address

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