Question

我有以下代码，我在其中为variant.pvarval调用VariantInit方法，因为我将把varaint存储在另一个名为pval的变种中。因此，在将值存储到/* #property "pragmas" help MQL4-compiler decide about setup of internal handlers so this part of code "speaks" to MetaLang.exe at compile-time*/ #property indicator_buffers 3 // .DEF N-Buffs #property indicator_color1 White // .SET Buf[0].color #property indicator_color2 SeaGreen // .SET Buf[1].color #property indicator_color3 FireBrick // .SET Buf[2].color #property indicator_width1 1 // .SET Buf[0].width #property indicator_width2 2 // .SET Buf[1].width #property indicator_width3 2 // .SET Buf[2].width double buffer_line_up[], // .DEF Arrays as dynamic ...[] buffer_line_dn[], // with human-readable-names buffer_line_ax[]; // and MT4 will take care int init() { SetIndexBuffer( 0, buffer_line_ax ); // .ASSOC IndexBuffer.0<-array[] SetIndexLabel( 0, "SuperTrend" ); SetIndexBuffer( 1, buffer_line_up ); // .ASSOC IndexBuffer.0<-array[] SetIndexLabel( 1, "Up Trend" ); SetIndexStyle( 1, DRAW_LINE, STYLE_SOLID, 1 + int( ATR_Multiplier / 5 ), SeaGreen ); SetIndexBuffer( 2, buffer_line_dn ); // .ASSOC IndexBuffer.0<-array[] SetIndexLabel( 2, "Down Trend" ); SetIndexStyle( 2, DRAW_LINE, STYLE_SOLID, 1 + int( ATR_Multiplier / 5 ), FireBrick ); SetIndexDrawBegin(0, ATR_Period ); // .DEF initial depth of Buffer before 1st GUI output IndicatorShortName( "xxxx[" + ATR_Period + "," + ATR_Multiplier + "]" ); IndicatorDigits( MarketInfo( Symbol(), MODE_DIGITS ) );之前，我正在为pVal->pvarVal调用VariantInit。但是电话pVal->pvarVal正在崩溃。

VariantInit(pVal->pvarVal)

Answer 1

来自在线帮助

VariantInit函数通过将vt成员设置为VT_EMPTY来初始化VARIANTARG。

此init函数不会将pvarVal初始化为任何有效的变量指针所以在你的代码中你有 pVal-> vt = VT_VARIANT | VT_BYREF;

    __int64 biNewVal =  // Some logic here
    pVal->pvarval=new VARIANT;
    pVal->pvarVal->vt = VT_CY;
    pVal->pvarVal->cyVal.int64 = biNewVal;

这样做会有效

如何初始化Variant pvarVal

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