为什么定义num时初始化或者用初始化函数Stu_t都会导致报错? 是不是意味着 union 内所有的成员以及嵌套的所有成员都不能在定义时初始化和使用构造函数呢? 如果不让初始化则会不会导致内存里是随机数据呢? typedef struct Stu_t { int num; // 或者 int num = 0; Stu_t () { Num = 0; } } Stu; typedef struct message_t { union result_t { int aaa; Stu stu; } result; } message; int main() { message msg; return 0; } 对 union 内成员逐层嵌套的成员进行定义时初始化和使用构造函数验证,发现都会报错。
刚开始学编程,vscode用make命令出现错误,插件装了环境也配置了,不知道哪里出问题,纯小白 源代码: #include #include int main(void) { printf ("hello world\n"); } 终端命令+错误提示: PS F:\Users\lyt\Desktop\c code> make hello cc hello.c -o hello process_begin: CreateProcess(NULL, cc hello.c -o hello, ...) failed. make (e=2): ?μí3?ò2?μ????¨μ????t?£ : recipe for target 'hello' failed make: * [hello] Error 2 PS F:\Users\lyt\Desktop\c code> 是哪里出问题了?要怎么解决?
使用vite打包组件库,打包出来的代码含有空值合并运算符?? ,导致安装的项目编译报错。实在是不知道哪里配错了,救救孩子吧~~vite.config.js配置如下。babel有升级到7。。。。 import { defineConfig } from "vite"; import react from "@vitejs/plugin-react"; import { libInjectCss } from "vite-plugin-lib-inject-css"; import babel from "@rollup/plugin-babel"; import vitePluginImp from "vite-plugin-imp"; export default defineConfig({ esbuild: { loader: "jsx", }, optimizeDeps: { esbuildOptions: { loader: { ".js": "jsx", }, }, }, plugins: [ react(), babel({ babelHelpers: "bundled", exclude: /node_modules/, plugins: ["@babel/plugin-transform-nullish-coalescing-operator"], presets: [ [ "@babel/preset-env", { targets: "> 0.25%, not dead", }, ], "@babel/preset-react", ], }), libInjectCss(), ], build: { outDir: "dist/umd", lib: { formats: ["umd"], entry: "lib/main.js", name: "DadaMobileUi", fileName: (format) => `dada-mobile-ui.${format}.js`, }, rollupOptions: { external: [ "react", "react-dom", "react/jsx-runtime", "prop-types", "@nutui/nutui-react", ], output: { globals: { react: "React", "react-dom": "ReactDOM", "react/jsx-runtime": "ReactJsxRuntime", "prop-types": "PropTypes", "@nutui/nutui-react": "nutuiReact", }, }, }, }, css: { plugins: [ require("autoprefixer")({ overrideBrowserslist: [ "> 0.5%", "last 2 versions", "ie > 11", "iOS >= 10", "Android >= 5", ], }), ], }, }); 实在是不知道哪里配错了,救救孩子吧