企业官网建设流程全解析

网站标题logo制作,北京公司网站开发,大连企业建站程序,宁夏网站建设联系电话string的构造string的默认构造是不能直接给空指针来进行初始化的在这里插入图片描述这种初始化在输出的时候程序就会崩溃#xff0c;由于还没有写流提取#xff0c;暂时用c_str输出#xff08;其返回的是底层的const char* #xff0c;自定义类型不支持#xff0c;但内置类…string的构造string的默认构造是不能直接给空指针来进行初始化的在这里插入图片描述这种初始化在输出的时候程序就会崩溃由于还没有写流提取暂时用c_str输出其返回的是底层的const char* 自定义类型不支持但内置类型支持在这里插入图片描述库里面的string就不会崩溃在这里插入图片描述代码语言javascriptAI代码解释const char* c_str() { return __str; // 如果 __str nullptr返回的就是空指针 } // 使用时 cout s1.c_str() endl;执行流程s1.c_str() 返回 nullptr地址 0cout 的 操作符接收到一个 const char* 参数 操作符内部会尝试读取该指针指向的内存内容【ostream::operator(const char*) 内部会调用类似 strlen() 的函数来确定字符串长度strlen(nullptr) 尝试从地址 0 开始逐个字节读取】直到遇到 \0 结束符。但由于指针是 nullptr程序尝试访问地址 0 的内存。地址 0 是受保护的操作系统通常将虚拟地址空间的低地址区域包括地址 0标记为不可访问。当程序尝试访问受保护的内存区域时操作系统会立即终止程序。所以string的默认构造的对象不能给空指针初始化库里面的string没有字符也至少有一个’\0’在这里插入图片描述在这里插入图片描述在这里插入图片描述该代码还可以优化strlen是一个ON的接口strlen是接收到一个串后将串中的字符遍历算一遍带参构造此处strlen算了三遍就效率不高了于是就有了下面的写法但是这样写程序会崩溃在这里插入图片描述初始化列表初始化的顺序是按声明的顺序走的初始化的时候依旧是先初始化_str此时size是随机值或0如果给0011。就只开了一个字节之后strcpy就会越界解决方法就是让_str和_capacity在函数体内初始化补充一下内置类型即使不在初始化列表显示初始化其他私有成员变量也会走一遍初始化列表这种就是隐式初始化了_str和_capacity两个内置类型会先在初始化列表被初始化可能是随机值再到函数体内被赋值map.fvblxbj.cn/Blog/595331.shtmlmap.fvblxbj.cn/Blog/957375.shtmlmap.fvblxbj.cn/Blog/339171.shtmlmap.fvblxbj.cn/Blog/119355.shtmlmap.fvblxbj.cn/Blog/713757.shtmlmap.fvblxbj.cn/Blog/711177.shtmlmap.fvblxbj.cn/Blog/937375.shtmlmap.fvblxbj.cn/Blog/971199.shtmlmap.fvblxbj.cn/Blog/357553.shtmlmap.fvblxbj.cn/Blog/373537.shtmlmap.fvblxbj.cn/Blog/511113.shtmlmap.fvblxbj.cn/Blog/511711.shtmlmap.fvblxbj.cn/Blog/171737.shtmlmap.fvblxbj.cn/Blog/804286.shtmlmap.fvblxbj.cn/Blog/157931.shtmlmap.fvblxbj.cn/Blog/133197.shtmlmap.fvblxbj.cn/Blog/751591.shtmlmap.fvblxbj.cn/Blog/173977.shtmlmap.fvblxbj.cn/Blog/915511.shtmlmap.fvblxbj.cn/Blog/519993.shtmlmap.fvblxbj.cn/Blog/133717.shtmlmap.fvblxbj.cn/Blog/333997.shtmlmap.fvblxbj.cn/Blog/737113.shtmlmap.fvblxbj.cn/Blog/338278.shtmlmap.fvblxbj.cn/Blog/711593.shtmlmap.fvblxbj.cn/Blog/119735.shtmlmap.fvblxbj.cn/Blog/935931.shtmlmap.fvblxbj.cn/Blog/313571.shtmlmap.fvblxbj.cn/Blog/771979.shtmlmap.fvblxbj.cn/Blog/575919.shtmlmap.fvblxbj.cn/Blog/862224.shtmlmap.fvblxbj.cn/Blog/886224.shtmlmap.fvblxbj.cn/Blog/042664.shtmlmap.fvblxbj.cn/Blog/191993.shtmlmap.fvblxbj.cn/Blog/020402.shtmlmap.fvblxbj.cn/Blog/648620.shtmlmap.fvblxbj.cn/Blog/620482.shtmlmap.fvblxbj.cn/Blog/880246.shtmlmap.fvblxbj.cn/Blog/862301.shtmlmap.fvblxbj.cn/Blog/913513.shtmlmap.fvblxbj.cn/Blog/719799.shtmlmap.fvblxbj.cn/Blog/911319.shtmlmap.fvblxbj.cn/Blog/402200.shtmlmap.fvblxbj.cn/Blog/800804.shtmlmap.fvblxbj.cn/Blog/462046.shtmlmap.fvblxbj.cn/Blog/062840.shtmlmap.fvblxbj.cn/Blog/600888.shtmlmap.fvblxbj.cn/Blog/759595.shtmlmap.fvblxbj.cn/Blog/739519.shtmlmap.fvblxbj.cn/Blog/995371.shtmlmap.fvblxbj.cn/Blog/371719.shtmlmap.fvblxbj.cn/Blog/406280.shtmlmap.fvblxbj.cn/Blog/939775.shtmlmap.fvblxbj.cn/Blog/991331.shtmlmap.fvblxbj.cn/Blog/535911.shtmlmap.fvblxbj.cn/Blog/779933.shtmlmap.fvblxbj.cn/Blog/393593.shtmlmap.fvblxbj.cn/Blog/191379.shtmlmap.fvblxbj.cn/Blog/208486.shtmlmap.fvblxbj.cn/Blog/222882.shtmlmap.fvblxbj.cn/Blog/664206.shtmlmap.fvblxbj.cn/Blog/280064.shtmlmap.fvblxbj.cn/Blog/793177.shtmlmap.fvblxbj.cn/Blog/775959.shtmlmap.fvblxbj.cn/Blog/428044.shtmlmap.fvblxbj.cn/Blog/137139.shtmlmap.fvblxbj.cn/Blog/157935.shtmlmap.fvblxbj.cn/Blog/973153.shtmlmap.fvblxbj.cn/Blog/488404.shtmlmap.fvblxbj.cn/Blog/957517.shtmlmap.fvblxbj.cn/Blog/379579.shtmlmap.fvblxbj.cn/Blog/573579.shtmlmap.fvblxbj.cn/Blog/357511.shtmlmap.fvblxbj.cn/Blog/648800.shtmlmap.fvblxbj.cn/Blog/153959.shtmlmap.fvblxbj.cn/Blog/688084.shtmlmap.fvblxbj.cn/Blog/648646.shtmlmap.fvblxbj.cn/Blog/666686.shtmlmap.fvblxbj.cn/Blog/680084.shtmlmap.fvblxbj.cn/Blog/200844.shtmlmap.fvblxbj.cn/Blog/755133.shtmlmap.fvblxbj.cn/Blog/353371.shtmlmap.fvblxbj.cn/Blog/353751.shtmlmap.fvblxbj.cn/Blog/266264.shtmlmap.fvblxbj.cn/Blog/468206.shtmlmap.fvblxbj.cn/Blog/553755.shtmlmap.fvblxbj.cn/Blog/351777.shtmlmap.fvblxbj.cn/Blog/757735.shtmlmap.fvblxbj.cn/Blog/551315.shtmlmap.fvblxbj.cn/Blog/177957.shtmlmap.fvblxbj.cn/Blog/551573.shtmlmap.fvblxbj.cn/Blog/484848.shtmlmap.fvblxbj.cn/Blog/222064.shtmlmap.fvblxbj.cn/Blog/604228.shtmlmap.fvblxbj.cn/Blog/351731.shtmlmap.fvblxbj.cn/Blog/195999.shtmlmap.fvblxbj.cn/Blog/353575.shtmlmap.fvblxbj.cn/Blog/179313.shtmlmap.fvblxbj.cn/Blog/753791.shtmlmap.fvblxbj.cn/Blog/151797.shtmlmap.fvblxbj.cn/Blog/339779.shtmlmap.fvblxbj.cn/Blog/393711.shtmlmap.fvblxbj.cn/Blog/795135.shtmlmap.fvblxbj.cn/Blog/715519.shtmlmap.fvblxbj.cn/Blog/195919.shtmlmap.fvblxbj.cn/Blog/915157.shtmlmap.fvblxbj.cn/Blog/735939.shtmlmap.fvblxbj.cn/Blog/533571.shtmlmap.fvblxbj.cn/Blog/515599.shtmlmap.fvblxbj.cn/Blog/959535.shtmlmap.fvblxbj.cn/Blog/779717.shtmlmap.fvblxbj.cn/Blog/466446.shtmlmap.fvblxbj.cn/Blog/337119.shtmlmap.fvblxbj.cn/Blog/713797.shtmlmap.fvblxbj.cn/Blog/177351.shtmlmap.fvblxbj.cn/Blog/519177.shtmlmap.fvblxbj.cn/Blog/551979.shtmlmap.fvblxbj.cn/Blog/335795.shtmlmap.fvblxbj.cn/Blog/737399.shtmlmap.fvblxbj.cn/Blog/137599.shtmlmap.fvblxbj.cn/Blog/791999.shtmlmap.fvblxbj.cn/Blog/559973.shtmlmap.fvblxbj.cn/Blog/157599.shtmlmap.fvblxbj.cn/Blog/313135.shtmlmap.fvblxbj.cn/Blog/319797.shtmlmap.fvblxbj.cn/Blog/979997.shtmlmap.fvblxbj.cn/Blog/355353.shtmlmap.fvblxbj.cn/Blog/391573.shtmlmap.fvblxbj.cn/Blog/533311.shtmlmap.fvblxbj.cn/Blog/313133.shtmlmap.fvblxbj.cn/Blog/733759.shtmlmap.fvblxbj.cn/Blog/197157.shtmlmap.fvblxbj.cn/Blog/379733.shtmlmap.fvblxbj.cn/Blog/573753.shtmlmap.fvblxbj.cn/Blog/137551.shtmlmap.fvblxbj.cn/Blog/179733.shtmlmap.fvblxbj.cn/Blog/377335.shtmlmap.fvblxbj.cn/Blog/191917.shtmlmap.fvblxbj.cn/Blog/113113.shtmlmap.fvblxbj.cn/Blog/797555.shtmlmap.fvblxbj.cn/Blog/335355.shtmlmap.fvblxbj.cn/Blog/971971.shtmlmap.fvblxbj.cn/Blog/753719.shtmlmap.fvblxb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