C++ std 没有成员“getline”？
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std has no member 'getline'?
提问by pighead10
I'm trying to use std::getline, but my compiler is telling me that getline isn't identified?
我正在尝试使用 std::getline，但是我的编译器告诉我 getline 没有被识别？
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <fstream>
#include <cstdlib>
int main(){
using namespace std;
string line;
ifstream ifile("test.in");
if(ifile.is_open()){
while(ifile.good()){
getline(ifile,line);
}
}
}
回答by ildjarn
std::getlineis defined in the stringheader.
std::getline在string头文件中定义。
#include <string>
Also, your code isn't using anything from cstring, cstdio, cmath, or cstdlib; why bother including these?
此外，您的代码没有使用cstring, cstdio, cmath, 或 中的任何内容cstdlib；为什么要包括这些？
EDIT:To clarify the confusion regarding the cstringand stringheaders, cstringpulls the contents of the C runtime library'sstring.hinto the stdnamespace; stringis part of the C++ standard libraryand contains getline, std::basic_string<>(and its specializations std::stringand std::wstring), etc. -- two verydifferent headers.
编辑：为了澄清关于cstring和string头文件的混淆，cstring将C 运行时库的内容拉string.h入std命名空间；string是C++ 标准库的一部分，包含getline, std::basic_string<>（及其专业化std::string和std::wstring）等——两个非常不同的头文件。
回答by pighead10
As ildjarn points out, the function is declared in <string>, and I'm suprised you didn't get an error at:
正如 ildjarn 指出的那样，该函数是在 中声明的<string>，我很惊讶您没有在以下位置收到错误：
string line;
Also, this:
还有这个：
while(ifile.good()){
getline(ifile,line);
}
is not the way to write a read loop. You MUST test the success of the read operation, not the current stream state. You want:
不是写读循环的方法。您必须测试读取操作的成功，而不是当前的流状态。你要：
while( getline(ifile,line) ) {
}
回答by FrostByte
this is happening because getline comes from the string library, you need to #include <string>or #include <cstring>
发生这种情况是因为 getline 来自字符串库，您需要#include <string>或#include <cstring>
