構(gòu)造函數(shù)2.0

為了解決對(duì)象初始化問題，于是，就提出了構(gòu)造函數(shù)這么一個(gè)策略。構(gòu)造函數(shù)有什么特點(diǎn)呢？一，函數(shù)名與類名相同。二，構(gòu)造函數(shù)沒有返回值。有如下代碼：

class Chair{
private:
    int legs;
public:
    void Setlegs ( int leg ){
        this->legs = leg;
    }
    int Getlegs ( void ){
        return this->legs;
    }
    Chair ( int leg ){
        this->legs = leg;
    }
};

int main ( int argc, char** argv ){
        Chair chair;             //編譯器會(huì)調(diào)用默認(rèn)構(gòu)造函數(shù)Chair();
        Chair chair1 ( 4 );   //調(diào)用構(gòu)造函數(shù)Chair( int leg );
        Chair chair2 = 4;    //調(diào)用構(gòu)造函數(shù)Chair ( int leg );

    system ( "pause" );
    return 0;
}

這段代碼，在類對(duì)象被創(chuàng)建后，那么，編譯器會(huì)為該對(duì)象分配相應(yīng)的空間大小并調(diào)用構(gòu)造函數(shù)。需要注意的是，類對(duì)象的聲明并不會(huì)為對(duì)象分配空間，只是告訴編譯器有這么一個(gè)對(duì)象存在。
構(gòu)造函數(shù)可以被編譯器自動(dòng)調(diào)用，那構(gòu)造函數(shù)可以手工調(diào)用嗎？當(dāng)然可以。比如，我們創(chuàng)建一個(gè)類數(shù)組，然后，我們對(duì)這個(gè)數(shù)組進(jìn)行進(jìn)行初始化。代碼如下：

#include <stdio.h>
#include <stdlib.h>

class Chair{

private:
    int legs;
public:
    int Getlegs ( void ){

        return this->legs;
    }
    void Setlegs ( int leg ){

        this->legs = leg;
    }
    Chair ( int leg ){

        this->legs = leg;
    }
    Chair ( void ){

        this->legs = 3;
    }

};

int main ( int argc, char** argv ){

    Chair chair[3] = { Chair ( 4 ), Chair ( 8 ), Chair() };
    int i;

    for ( i = 0; i < 3; ++i ){

        printf ( "%d\n", chair[i].Getlegs() );
    }

    system ( "pause" );
    return 0;
}

運(yùn)行代碼如下：

除此之外，還有一種手工調(diào)用構(gòu)造函數(shù)的方式：

Chair chair = Chair ( 4 );

其實(shí)這種手工調(diào)用構(gòu)造函數(shù)的方式，也可以說是初始化類對(duì)象的另外一種方式。