combobox 槽函数 怎么改啊

Question

int G；

if (G = 1) part->SetFileName("standard_ankle.stl");
else if (G = 2) part->SetFileName("standard_elbow.stl");
else if (G = 3) part->SetFileName("standard_wrist.stl");
else if (G = 4) part->SetFileName("standard_wrist_st.stl");
//这个在主类里面d
void QtGuiApplication4::Standardslot()
{
if (ui->comboBox->currentIndex() == 1) G = 1;
else if (ui->comboBox->currentIndex() == 2) G = 2;
else if (ui->comboBox->currentIndex() == 3) G = 3;
else if (ui->comboBox->currentIndex() == 4) G = 4;
}
为啥在下拉框点击1，2，3，4后，qvtkwidget没有反应e

Answer 1

if (G = 1)
->
if (G == 1)