GLFW_PRESS 抛出 "lvalue required as left operand of assignment"

Question

我正在尝试使用文档中提供的代码制作一个简单的 GLFW 键回调函数：

void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
    if (key == GLFW_KEY_W && action = GLFW_PRESS) {
        glTranslatef(0.25f, 0, 0);
    }
    if (key == GLFW_KEY_A && action = GLFW_PRESS) {
        glTranslatef(0, 0, 0.25f);
    }
    if (key == GLFW_KEY_S && action = GLFW_PRESS) {
        glTranslatef(-0.25f, 0, 0);
    }
    if (key == GLFW_KEY_D && action = GLFW_PRESS) {
        glTranslatef(0, 0, -0.25f);
    }
}

但是，G++ 抛出错误：

glfw3.h:310:37: error: lvalue required as left operand of assignment
  310 | #define GLFW_PRESS                  1
      |                                     ^
main.cpp:70:36: note: in expansion of macro 'GLFW_PRESS'
   70 |  if (key == GLFW_KEY_W && action = GLFW_PRESS) {

对于这些“if”语句中的每一个。

我在用这个命令编译的时候遇到的： g++ main.cpp -lopengl32 -lglu32 -lglfw3 -mwindows。我已经正确安装了带有 MinGW 的 GLFW，它可以自行编译。

Answer 1

问题是语法错误，使用 = 而不是 ==。

GLFW_PRESS 抛出 "lvalue required as left operand of assignment"

GLFW_PRESS throws "lvalue required as left operand of assignment"

c++

opengl

g++

glfw