Initialization of variables

Overview

Variables can be initialized during their definition.

Implicit initialization is not used; uninitialized variables hold arbitrary values.

Initialization Rules by Scope

**Global and Static Variables:**

* Can only be initialized by a constant of the corresponding type or a constant expression. * Initialization is performed only once.

**Local Variables:**

* Can be initialized by any expression, not just a constant. * Initialization is performed every time the corresponding function is called.

Array and Structure Initialization

**General:**

* List of values must be enclosed in curly brackets {}. * Missed initializing sequences are considered equal to 0. * The initializing sequence must have at least one value. * If the array size is not specified, it is determined by the compiler based on the initialization sequence size.

**Multi-dimensional Arrays:**

* Cannot be initialized by a one-dimensional sequence (without additional curly brackets), unless only one initializing element is specified (typically zero).

**Arrays (including local):**

* Can only be initialized by constants.

**Structures:**

* Partial initialization is allowed. * You can initialize one or more first elements; other elements will be initialized with zeroes.

Examples

**Simple Variables:**

    int n = 1;
    string s = "hello";
    double f[] = { 0.0, 0.236, 0.382, 0.5, 0.618, 1.0 };
    int a[4][4] = { {1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4} };
    int right[4]={WIDTH_IN_PIXELS+VERT_BORDER, WIDTH_IN_PIXELS+VERT_BORDER, WIDTH_IN_PIXELS+VERT_BORDER, WIDTH_IN_PIXELS+VERT_BORDER};
    MqlTradeRequest request={0}; // Initializes all structure fields to zero

**Complex Structure Initialization:**

    struct str3 { int low_part; int high_part; };
    struct str10 { str3 s3; double d1[10]; int i3; };    // Example usage within a function:
    // str10 s10_1={{1,0},{1.0,2.1,3.2,4.4,5.3,6.1,7.8,8.7,9.2,10.0},100};
    // str10 s10_2={{1,0},{0},100}; // Initializes d1[0] to 0, rest to 0
    // str10 s10_3={{1,0},{1.0},100}; // Initializes d1[0] to 1.0, rest to 0

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