如何在 C++ 中使用 scanf 扫描字符串
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How to scan a string using scanf with C++
提问by user3097544
I have tried most of the string and char format types and they are not working and I have no Idea why. Here is my code :
我已经尝试了大多数字符串和字符格式类型，但它们不起作用，我不知道为什么。这是我的代码：
#include <iostream>
#include <stdio.h>
using namespace std;
int main(int argc, const char * argv[])
{
// insert code here...
string string2;
string string;
cout << "Hello, World!\n";
printf("Hi my name is Josh %s\n",string2);
scanf("%s",&string);
printf("hi %s",string);
}
回答by π?ντα ?ε?
What you're showing (scanf("%s",&string);) doesn't work (and never could, by e.g. giving different format specifiers)!
您显示的 ( scanf("%s",&string);) 不起作用（并且永远不会，例如通过提供不同的格式说明符）！
scanf()used with the %sformat specifier requires a corresponding char*pointer referencing a raw char[]array to receive the read data in the parameter list. The std::stringpointer you're passing in your example, doesn't provide automatic casting to the referred std::stringinstances internally managed char[]buffer that way though.
scanf()与%s格式说明符一起使用需要一个char*引用原始char[]数组的相应指针来接收参数列表中的读取数据。std::string您在示例中传递的指针并没有以这种方式提供对std::string内部管理char[]缓冲区的引用实例的自动转换。
You could try to use &string.front()instead, but I wouldn't really recommend that, unless you're very sure what you're doing.
您可以尝试&string.front()改用，但我真的不建议这样做，除非您非常确定自己在做什么。
For c++you should better use std::cinandstd::istream& operator>>(std::istream&, const std::string&)instead:
对于C++，你应该更好地使用std::cin，std::istream& operator>>(std::istream&, const std::string&)而不是：
std::cout << "Put in string value:" << std::endl;
std::string input;
std::cin >> input;
(xcodeisn't relevant for your question BTW!)
（顺便说一句，xcode与您的问题无关！）
回答by Johnsyweb
You shouldn't mix std::coutwith ::printf. Prefer to use the C++ Standard IO libraryover C functions from stdio.
你不应该std::cout与::printf. 更喜欢使用C++ 标准 IO 库而不是来自stdio.
Your code should look a little like this:
您的代码应该如下所示：
#include <iostream>
int main()
{
std::string string2;
std::string other_string;
std::cout << "Hello, World!\n";
std::cout << "Hi my name is Josh " << string2 << '\n';
std::cin >> other_string;
std::cout << "hi " << other_string;
}
