{"id":14859,"date":"2024-03-15T10:05:24","date_gmt":"2024-03-15T10:05:24","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-to-use-the-const-qualifier-in-c\/"},"modified":"2025-08-06T13:43:15","modified_gmt":"2025-08-06T13:43:15","slug":"how-to-use-the-const-qualifier-in-c","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-to-use-the-const-qualifier-in-c\/","title":{"rendered":"How to use the const qualifier in C++?"},"content":{"rendered":"

In C++, the const qualifier is used to modify variables, function parameters, and function return values. It informs the compiler that the item is constant and cannot be changed.<\/p>\n

    \n
  1. Modify variables.<\/li>\n<\/ol>\n
    const<\/span> int<\/span> num = 10<\/span>; \/\/ \u5e38\u91cfnum\u7684\u503c\u4e0d\u80fd\u88ab\u4fee\u6539<\/span>\r\n<\/code><\/pre>\n
      \n
    1. Modify function parameters.<\/li>\n<\/ol>\n
      void<\/span> func<\/span>(const<\/span> int<\/span> num)<\/span> <\/span>{\r\n    \/\/ \u51fd\u6570\u4f53<\/span>\r\n}\r\n<\/code><\/pre>\n
      In this example, the parameter num of the function func is declared as a constant, and its value cannot be changed within the function body.<\/p>\n
        \n
      1. Modifying the function return value:<\/li>\n<\/ol>\n
        const<\/span> int<\/span> func<\/span>()<\/span> <\/span>{\r\n    \/\/ \u51fd\u6570\u4f53<\/span>\r\n    return<\/span> 10<\/span>;\r\n}\r\n<\/code><\/pre>\n
        In this example, the returned value of the function “func” is declared as a constant, indicating that the value cannot be modified.<\/p>\n
        It is important to note that the const qualifier must come before the type name and constants must be initialized at the declaration. Additionally, when const is used to modify an object, it ensures that the object’s initial value cannot be changed. Furthermore, the const qualifier can also be used with reference types to declare a reference that cannot be modified.<\/p>\n","protected":false},"excerpt":{"rendered":"
        In C++, the const qualifier is used to modify variables, function parameters, and function return values. It informs the compiler that the item is constant and cannot be changed. Modify variables. const int num = 10; \/\/ \u5e38\u91cfnum\u7684\u503c\u4e0d\u80fd\u88ab\u4fee\u6539 Modify function parameters. void func(const int num) { \/\/ \u51fd\u6570\u4f53 } In this example, the parameter num […]<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[453,1402,299,1404,1403],"class_list":["post-14859","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-development","tag-guide","tag-programming","tag-technology","tag-tutorial"],"yoast_head":"\nHow to use the const qualifier in C++? - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"Learn about how to use the const qualifier in c++?. 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