c - C 语言的 Opencv 库。这条指令到底是做什么的 int=pointer==0; ？

Question

CvMat* nextimg = 0;
int firstframe;


firstframe=nextimg==0;

如果我不输入“==0”，则会返回以下警告:

[Warning] assignment makes integer from pointer without a cast

Answer 1

它是一个缩短的等价物

int firstframe;
if (nextimg == 0) {
    firstframe = 1;
}
else {
    firstframe = 0;
}